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These are the user uploaded subtitles that are being translated: 1 00:00:00,080 --> 00:00:02,399 so i bought a petrol pump nozzle and cut 2 00:00:02,399 --> 00:00:04,640 it in half you might call it a gas pump 3 00:00:04,640 --> 00:00:06,799 nozzle the reason i cut it in half is 4 00:00:06,799 --> 00:00:09,280 because i want to answer one question 5 00:00:09,280 --> 00:00:11,599 how do these things know when to turn 6 00:00:11,599 --> 00:00:14,480 themselves off you hear that click sound 7 00:00:14,480 --> 00:00:16,320 that's the nozzle turning itself off 8 00:00:16,320 --> 00:00:18,560 like when you go to fill up your car 9 00:00:18,560 --> 00:00:20,800 with petrol you don't have to worry 10 00:00:20,800 --> 00:00:23,199 about it overflowing that's because 11 00:00:23,199 --> 00:00:25,680 these nozzles switch off automatically 12 00:00:25,680 --> 00:00:28,320 when the tank is full but how my first 13 00:00:28,320 --> 00:00:29,599 thought was that there must be some kind 14 00:00:29,599 --> 00:00:31,840 of electronic sensor in there but the 15 00:00:31,840 --> 00:00:34,320 way these really work is much smarter 16 00:00:34,320 --> 00:00:36,160 than that there are actually two very 17 00:00:36,160 --> 00:00:38,399 clever mechanisms in here the first one 18 00:00:38,399 --> 00:00:41,200 relates to this tube you can see that 19 00:00:41,200 --> 00:00:43,120 runs to the end of the nozzle and the 20 00:00:43,120 --> 00:00:45,680 second relates to all these connected 21 00:00:45,680 --> 00:00:48,320 levers the whole thing's quite compact 22 00:00:48,320 --> 00:00:50,239 so i built a few different things to 23 00:00:50,239 --> 00:00:52,879 illustrate each part of the mechanism to 24 00:00:52,879 --> 00:00:55,039 make it clearer let's start with this 25 00:00:55,039 --> 00:00:58,399 hole that's usually located here or here 26 00:00:58,399 --> 00:01:00,320 it's called the venturi sensor which 27 00:01:00,320 --> 00:01:02,320 sounds like it's electronic but actually 28 00:01:02,320 --> 00:01:05,760 this is entirely fluid mechanical it's 29 00:01:05,760 --> 00:01:07,360 called the venturi sensor because it 30 00:01:07,360 --> 00:01:09,840 works on the venturi effect the venturi 31 00:01:09,840 --> 00:01:12,240 effect happens in this part of the 32 00:01:12,240 --> 00:01:14,799 nozzle but to be able to see what's 33 00:01:14,799 --> 00:01:17,360 going on i got this made it's called a 34 00:01:17,360 --> 00:01:19,520 venturi tube because it demonstrates the 35 00:01:19,520 --> 00:01:22,400 venturi effect it's a wide tube that 36 00:01:22,400 --> 00:01:24,080 narrows in the middle and then you have 37 00:01:24,080 --> 00:01:26,479 this narrow u-bend-shaped tube coming 38 00:01:26,479 --> 00:01:28,000 off the restriction in the middle there 39 00:01:28,000 --> 00:01:30,159 are two other u-bend shaped tubes either 40 00:01:30,159 --> 00:01:32,560 side but we're ignoring those for now 41 00:01:32,560 --> 00:01:34,720 look what happens when i partially fill 42 00:01:34,720 --> 00:01:37,040 this u-bend with water and then blow 43 00:01:37,040 --> 00:01:39,360 through the tube you might expect air to 44 00:01:39,360 --> 00:01:41,920 be forced into the u-bend causing the 45 00:01:41,920 --> 00:01:44,960 level of water here to go down in fact 46 00:01:44,960 --> 00:01:48,000 the water level here goes up that means 47 00:01:48,000 --> 00:01:50,159 there must be a reduction in pressure 48 00:01:50,159 --> 00:01:52,560 here in the constriction and that's 49 00:01:52,560 --> 00:01:54,560 sucking the water up by the way the 50 00:01:54,560 --> 00:01:56,560 water in the u-bend is there just so 51 00:01:56,560 --> 00:01:59,280 that you can see the change in pressure 52 00:01:59,280 --> 00:02:01,040 there's no equivalent to that water in 53 00:02:01,040 --> 00:02:03,439 the nozzle itself but why does the 54 00:02:03,439 --> 00:02:06,399 pressure go down well it's bernoulli's 55 00:02:06,399 --> 00:02:08,399 principle but actually we can explain it 56 00:02:08,399 --> 00:02:10,560 quite easily from first principles the 57 00:02:10,560 --> 00:02:12,319 air travelling through the constricted 58 00:02:12,319 --> 00:02:14,319 part of the pipe must be traveling 59 00:02:14,319 --> 00:02:17,040 faster than the air in the wider part of 60 00:02:17,040 --> 00:02:19,760 the pipe that makes intuitive sense to 61 00:02:19,760 --> 00:02:21,360 get the same amount of mass through a 62 00:02:21,360 --> 00:02:23,520 narrower pipe the mass must have to 63 00:02:23,520 --> 00:02:25,599 travel more quickly but you can also 64 00:02:25,599 --> 00:02:27,520 think about it in terms of conservation 65 00:02:27,520 --> 00:02:30,560 of energy the gas here has kinetic 66 00:02:30,560 --> 00:02:32,959 energy but it also has potential energy 67 00:02:32,959 --> 00:02:35,040 stored as pressure a bit like how you 68 00:02:35,040 --> 00:02:37,760 can store energy in a spring by 69 00:02:37,760 --> 00:02:39,200 compressing it 70 00:02:39,200 --> 00:02:42,000 but that total energy kinetic energy 71 00:02:42,000 --> 00:02:44,879 plus potential energy stored as pressure 72 00:02:44,879 --> 00:02:46,879 needs to be conserved 73 00:02:46,879 --> 00:02:48,959 that means that when the kinetic energy 74 00:02:48,959 --> 00:02:51,360 goes up in the fast-moving fluid in the 75 00:02:51,360 --> 00:02:53,360 constricted part of the tube the 76 00:02:53,360 --> 00:02:55,599 potential energy must go down the 77 00:02:55,599 --> 00:02:57,920 pressure must go down by the way those 78 00:02:57,920 --> 00:03:00,319 two other u-bend shaped tubes either 79 00:03:00,319 --> 00:03:01,760 side of the middle one are there to 80 00:03:01,760 --> 00:03:03,280 illustrate the fact that the pressure 81 00:03:03,280 --> 00:03:05,760 goes down in the wider parts of the tube 82 00:03:05,760 --> 00:03:07,760 as well when there's air flowing but 83 00:03:07,760 --> 00:03:09,920 just not to the same degree as it does 84 00:03:09,920 --> 00:03:12,400 in the constricted part of the tube the 85 00:03:12,400 --> 00:03:14,319 two outer u-shaped pipes have nothing to 86 00:03:14,319 --> 00:03:16,800 do with the discussion we're having here 87 00:03:16,800 --> 00:03:18,959 about petrol nozzles i just thought i 88 00:03:18,959 --> 00:03:20,959 should explain what they were but 89 00:03:20,959 --> 00:03:23,519 thinking about that central u-shaped 90 00:03:23,519 --> 00:03:26,319 tube what does that tell us about how 91 00:03:26,319 --> 00:03:29,200 the petrol nozzle works well this pipe 92 00:03:29,200 --> 00:03:32,239 in the model is this pipe in the nozzle 93 00:03:32,239 --> 00:03:34,239 the constriction in the pipe that 94 00:03:34,239 --> 00:03:36,239 happens here in the model actually 95 00:03:36,239 --> 00:03:38,720 happens here in the nozzle this 96 00:03:38,720 --> 00:03:40,879 spring-loaded stopper here opens 97 00:03:40,879 --> 00:03:42,239 slightly under the pressure of the 98 00:03:42,239 --> 00:03:45,360 petrol to reveal a really narrow ring 99 00:03:45,360 --> 00:03:47,120 for the liquid to pass through and you 100 00:03:47,120 --> 00:03:49,680 can just about see inside that ring 101 00:03:49,680 --> 00:03:51,680 there's a tiny hole there actually 102 00:03:51,680 --> 00:03:53,360 there's a number of holes the one i just 103 00:03:53,360 --> 00:03:55,280 illustrated with the paperclip there's 104 00:03:55,280 --> 00:03:57,200 also this one and there's probably one 105 00:03:57,200 --> 00:03:59,040 on the other side as well but they all 106 00:03:59,040 --> 00:04:01,519 lead up to here and then into this hole 107 00:04:01,519 --> 00:04:03,680 which comes down through here 108 00:04:03,680 --> 00:04:08,319 which feeds into this long tube 109 00:04:08,400 --> 00:04:10,400 this tube that runs to the end of the 110 00:04:10,400 --> 00:04:12,640 petrol pump nozzle is equivalent to this 111 00:04:12,640 --> 00:04:15,680 tube in the model so this constriction 112 00:04:15,680 --> 00:04:18,560 here creates low pressure in the tube 113 00:04:18,560 --> 00:04:20,798 there is low pressure here at the end of 114 00:04:20,798 --> 00:04:23,040 the nozzle that means air is actually 115 00:04:23,040 --> 00:04:25,680 drawn in through this tube that air 116 00:04:25,680 --> 00:04:28,400 simply mixes with the petrol in this 117 00:04:28,400 --> 00:04:30,479 part of the nozzle so how is this used 118 00:04:30,479 --> 00:04:32,960 to detect when your petrol tank or your 119 00:04:32,960 --> 00:04:35,120 gas tank is full this bit's really 120 00:04:35,120 --> 00:04:37,440 clever the tube that comes away from the 121 00:04:37,440 --> 00:04:39,520 constriction in the flow of the main 122 00:04:39,520 --> 00:04:42,960 pipe is actually forked one tube goes 123 00:04:42,960 --> 00:04:44,880 off to the end of the nozzle as we've 124 00:04:44,880 --> 00:04:47,520 seen but there's actually a second tube 125 00:04:47,520 --> 00:04:50,080 that goes off up here because of the way 126 00:04:50,080 --> 00:04:52,160 this thing has been cut in half it's not 127 00:04:52,160 --> 00:04:54,400 that easy to see but there is a tube 128 00:04:54,400 --> 00:04:56,400 coming off here most of it's been cut 129 00:04:56,400 --> 00:04:59,040 away but it was there and that tube 130 00:04:59,040 --> 00:05:02,000 leads to this cavity here that cavity is 131 00:05:02,000 --> 00:05:04,240 sealed by a membrane you can see part of 132 00:05:04,240 --> 00:05:06,560 the membrane just there before it was 133 00:05:06,560 --> 00:05:08,880 cut in half in other words before i cut 134 00:05:08,880 --> 00:05:11,120 it in half this whole chamber was sealed 135 00:05:11,120 --> 00:05:13,520 off with a membrane so schematically it 136 00:05:13,520 --> 00:05:15,919 would look like this with two tubes 137 00:05:15,919 --> 00:05:18,160 forking off the restriction this now 138 00:05:18,160 --> 00:05:19,840 represents the tube that goes to the end 139 00:05:19,840 --> 00:05:21,680 of the nozzle and this represents the 140 00:05:21,680 --> 00:05:24,240 tube that goes to the sealed chamber so 141 00:05:24,240 --> 00:05:26,240 when i blow through this pipe it will 142 00:05:26,240 --> 00:05:28,800 reduce the pressure in this tube and 143 00:05:28,800 --> 00:05:30,000 this tube 144 00:05:30,000 --> 00:05:31,680 but look what happens when i put my 145 00:05:31,680 --> 00:05:33,520 finger over this tube 146 00:05:33,520 --> 00:05:35,440 it turns out that this tube was 147 00:05:35,440 --> 00:05:38,080 relieving some of the negative pressure 148 00:05:38,080 --> 00:05:40,320 and when i put my finger over it look 149 00:05:40,320 --> 00:05:42,800 you see a sudden jump in the water level 150 00:05:42,800 --> 00:05:45,440 in this tube the same thing happens with 151 00:05:45,440 --> 00:05:47,600 the petrol nozzle this opening is 152 00:05:47,600 --> 00:05:49,520 allowing some of that negative pressure 153 00:05:49,520 --> 00:05:52,560 to be relieved by allowing air to flow 154 00:05:52,560 --> 00:05:54,479 into the system but then what happens 155 00:05:54,479 --> 00:05:56,479 when the level of petrol in your tank 156 00:05:56,479 --> 00:05:58,880 reaches the end of the nozzle well it 157 00:05:58,880 --> 00:06:01,120 covers up that hole the tube is now 158 00:06:01,120 --> 00:06:04,160 sucking on petrol instead of air petrol 159 00:06:04,160 --> 00:06:06,720 is heavier than air so the tube can't 160 00:06:06,720 --> 00:06:09,680 suck as much it can't relieve as much of 161 00:06:09,680 --> 00:06:12,160 that suction force and just like when i 162 00:06:12,160 --> 00:06:15,039 put my finger over one pipe in the model 163 00:06:15,039 --> 00:06:17,680 the other pipe experiences an increase 164 00:06:17,680 --> 00:06:19,680 in suction force this is my attempt to 165 00:06:19,680 --> 00:06:22,160 put all that together so you've got the 166 00:06:22,160 --> 00:06:25,360 main tube it has a constriction here 167 00:06:25,360 --> 00:06:27,440 here's the tube coming off from the 168 00:06:27,440 --> 00:06:30,160 constriction here is where it forks one 169 00:06:30,160 --> 00:06:32,319 tube goes to the end of the nozzle the 170 00:06:32,319 --> 00:06:34,479 other goes to this chamber that's sealed 171 00:06:34,479 --> 00:06:37,120 off with a membrane here 172 00:06:37,120 --> 00:06:39,199 and look when the liquid in the tank 173 00:06:39,199 --> 00:06:41,680 reaches the end of the venturi tube you 174 00:06:41,680 --> 00:06:44,319 see that membrane gets sucked into the 175 00:06:44,319 --> 00:06:46,160 chamber the membrane moves up only 176 00:06:46,160 --> 00:06:48,720 slightly in my model that's because i 177 00:06:48,720 --> 00:06:51,120 don't know much about fluid dynamics i'm 178 00:06:51,120 --> 00:06:52,800 sure there's a lot of things i could 179 00:06:52,800 --> 00:06:55,759 tune in this model like how much is the 180 00:06:55,759 --> 00:06:57,440 pipe constricted how wide are the 181 00:06:57,440 --> 00:06:59,759 venturi tubes where does the fork happen 182 00:06:59,759 --> 00:07:02,000 all that sort of stuff but for me it was 183 00:07:02,000 --> 00:07:04,160 incredibly satisfying to see that 184 00:07:04,160 --> 00:07:07,039 membrane move at all so when the petrol 185 00:07:07,039 --> 00:07:08,960 in your tank reaches the end of the 186 00:07:08,960 --> 00:07:11,840 nozzle this membrane moves and you'll 187 00:07:11,840 --> 00:07:14,160 notice that this membrane is attached to 188 00:07:14,160 --> 00:07:17,360 something it's attached to this rod here 189 00:07:17,360 --> 00:07:19,360 and that's really important that's how 190 00:07:19,360 --> 00:07:21,599 the nozzle actually turns off it's quite 191 00:07:21,599 --> 00:07:23,199 hard to see what's going on here so i 192 00:07:23,199 --> 00:07:25,840 built another model so imagine this is a 193 00:07:25,840 --> 00:07:28,080 valve that lets petrol through i need to 194 00:07:28,080 --> 00:07:30,720 push this thing up to open the valve in 195 00:07:30,720 --> 00:07:32,400 the actual nozzle this valve is 196 00:07:32,400 --> 00:07:33,840 spring-loaded 197 00:07:33,840 --> 00:07:36,400 in this model i'm representing that fact 198 00:07:36,400 --> 00:07:37,919 with a mass 199 00:07:37,919 --> 00:07:40,080 the mass is pushing back down on the 200 00:07:40,080 --> 00:07:42,720 valve like the spring in the real thing 201 00:07:42,720 --> 00:07:45,840 and this here is the handle of the pump 202 00:07:45,840 --> 00:07:48,319 so hopefully if i pull this handle up it 203 00:07:48,319 --> 00:07:50,960 will open the valve but look it doesn't 204 00:07:50,960 --> 00:07:53,440 actually work because we've got a lever 205 00:07:53,440 --> 00:07:55,919 happening here pulling the handle up 206 00:07:55,919 --> 00:07:58,400 just makes this thing move down what i 207 00:07:58,400 --> 00:08:01,280 need to do is hold this thing in place 208 00:08:01,280 --> 00:08:03,360 so that this becomes the fulcrum of the 209 00:08:03,360 --> 00:08:04,479 lever 210 00:08:04,479 --> 00:08:06,800 now when i pull the handle up it opens 211 00:08:06,800 --> 00:08:10,000 the valve great now one way i can hold 212 00:08:10,000 --> 00:08:12,000 this thing in place is to put a couple 213 00:08:12,000 --> 00:08:15,280 of circles in here 214 00:08:18,160 --> 00:08:20,879 and then i put this piece in to hold 215 00:08:20,879 --> 00:08:23,360 these circles in place to stop them 216 00:08:23,360 --> 00:08:25,039 falling into the middle 217 00:08:25,039 --> 00:08:27,440 and there you go that works perfectly 218 00:08:27,440 --> 00:08:29,599 now here's the clever part 219 00:08:29,599 --> 00:08:31,919 this funny wedge thing is attached to 220 00:08:31,919 --> 00:08:34,240 the membrane and remember when petrol 221 00:08:34,240 --> 00:08:36,880 reaches that venturi tube it causes the 222 00:08:36,880 --> 00:08:39,360 membrane to pop up and when it pops up 223 00:08:39,360 --> 00:08:41,279 it pulls this part with it 224 00:08:41,279 --> 00:08:43,839 and when it does that those circles are 225 00:08:43,839 --> 00:08:45,920 now free to fall into the middle they're 226 00:08:45,920 --> 00:08:47,920 no longer jamming that shaft in place 227 00:08:47,920 --> 00:08:50,480 and this point stops being the fulcrum 228 00:08:50,480 --> 00:08:53,040 everything collapses and the valve shuts 229 00:08:53,040 --> 00:08:54,800 in three dimensions this is achieved 230 00:08:54,800 --> 00:08:57,440 with three ball bearings in these two 231 00:08:57,440 --> 00:08:59,360 positions and one round the back that 232 00:08:59,360 --> 00:09:01,200 you can't see so let's put all those 233 00:09:01,200 --> 00:09:03,279 mechanisms together inside the nozzle 234 00:09:03,279 --> 00:09:05,760 itself and recap so petrol comes in here 235 00:09:05,760 --> 00:09:07,920 under pressure and it meets this closed 236 00:09:07,920 --> 00:09:10,560 valve so you pull on this handle here 237 00:09:10,560 --> 00:09:12,320 you'll notice it doesn't open the valve 238 00:09:12,320 --> 00:09:15,120 instead this thing moves but look you 239 00:09:15,120 --> 00:09:17,040 get to this point here and these ball 240 00:09:17,040 --> 00:09:20,000 bearings they get jammed against the 241 00:09:20,000 --> 00:09:22,399 constriction here in the housing of 242 00:09:22,399 --> 00:09:23,760 course because i've cut this thing in 243 00:09:23,760 --> 00:09:25,600 half that doesn't work the constriction 244 00:09:25,600 --> 00:09:27,600 doesn't work and the thing can move when 245 00:09:27,600 --> 00:09:28,880 it shouldn't so i'm just going to use 246 00:09:28,880 --> 00:09:30,640 brute force to hold that in place to 247 00:09:30,640 --> 00:09:33,600 illustrate the point and look now 248 00:09:33,600 --> 00:09:35,519 i've lost a ball bang doesn't matter now 249 00:09:35,519 --> 00:09:37,519 when i put on this handle this point 250 00:09:37,519 --> 00:09:39,600 acts as a fulcrum and 251 00:09:39,600 --> 00:09:42,320 the lever mechanism opens the valve and 252 00:09:42,320 --> 00:09:44,560 petrol can flow through 253 00:09:44,560 --> 00:09:47,200 so let's imagine the valve is still open 254 00:09:47,200 --> 00:09:49,040 petrol flows through here it looks as if 255 00:09:49,040 --> 00:09:51,279 this housing is in the way of the petrol 256 00:09:51,279 --> 00:09:52,720 but actually there's a gap underneath 257 00:09:52,720 --> 00:09:54,320 and there's a gap on the top as well so 258 00:09:54,320 --> 00:09:56,320 petrol flows around this part of the 259 00:09:56,320 --> 00:09:57,839 mechanism and then the pressure of the 260 00:09:57,839 --> 00:10:00,160 petrol pushes against this spring-loaded 261 00:10:00,160 --> 00:10:02,320 thing here which creates a thin circular 262 00:10:02,320 --> 00:10:03,839 channel for the petrol to continue to 263 00:10:03,839 --> 00:10:06,480 flow through the nozzle 264 00:10:06,480 --> 00:10:09,200 now because it's a thin channel and due 265 00:10:09,200 --> 00:10:11,040 to the venturi effect the pressure is 266 00:10:11,040 --> 00:10:13,200 lower in that part and look there's a 267 00:10:13,200 --> 00:10:15,360 hole here and a hole here that links to 268 00:10:15,360 --> 00:10:18,160 that low pressure region and that hole 269 00:10:18,160 --> 00:10:20,720 leads over here down into this tube but 270 00:10:20,720 --> 00:10:22,640 it also goes up into 271 00:10:22,640 --> 00:10:25,120 this cavity here that is bounded by a 272 00:10:25,120 --> 00:10:27,200 membrane at the bottom here it's cut in 273 00:10:27,200 --> 00:10:28,800 half now 274 00:10:28,800 --> 00:10:31,920 because this hole is open to the air it 275 00:10:31,920 --> 00:10:34,560 sucks air in and that acts to relieve 276 00:10:34,560 --> 00:10:36,320 the negative pressure 277 00:10:36,320 --> 00:10:38,800 but when your petrol tank is full and it 278 00:10:38,800 --> 00:10:40,399 comes up to that hole 279 00:10:40,399 --> 00:10:42,079 it's harder to suck on petrol than it is 280 00:10:42,079 --> 00:10:44,560 to suck on air so this tube here is less 281 00:10:44,560 --> 00:10:46,959 good at relieving that negative pressure 282 00:10:46,959 --> 00:10:49,279 which means that this chamber here feels 283 00:10:49,279 --> 00:10:51,519 a stronger negative pressure which pulls 284 00:10:51,519 --> 00:10:53,200 up on the membrane the membrane is 285 00:10:53,200 --> 00:10:54,800 attached to this thing so this thing 286 00:10:54,800 --> 00:10:56,800 gets pulled up as well so let's put all 287 00:10:56,800 --> 00:10:58,399 that together at the very end and see 288 00:10:58,399 --> 00:11:00,959 what happens when the petrol nozzle in 289 00:11:00,959 --> 00:11:03,600 your hand makes that clicking sound 290 00:11:03,600 --> 00:11:05,839 so the ball bearings are holding this 291 00:11:05,839 --> 00:11:08,320 thing in place and look you've opened 292 00:11:08,320 --> 00:11:11,920 the valve but now like this thing i can 293 00:11:11,920 --> 00:11:13,760 try and reach over and this thing lifts 294 00:11:13,760 --> 00:11:15,760 up you see the ball bearings fall into 295 00:11:15,760 --> 00:11:17,279 the middle of that thing which means it 296 00:11:17,279 --> 00:11:19,519 can now slide down which causes this 297 00:11:19,519 --> 00:11:21,200 thing to move down which causes this 298 00:11:21,200 --> 00:11:22,560 thing to move down 299 00:11:22,560 --> 00:11:24,800 which closes the valve and of course 300 00:11:24,800 --> 00:11:27,040 that prevents petrol from spilling out 301 00:11:27,040 --> 00:11:28,800 of your full tank onto the full court 302 00:11:28,800 --> 00:11:31,040 which would be a pretty big fire hazard 303 00:11:31,040 --> 00:11:33,360 this video is sponsored by 80 000 hours 304 00:11:33,360 --> 00:11:35,440 a non-profit that helps people to find 305 00:11:35,440 --> 00:11:37,600 careers that solve the world's biggest 306 00:11:37,600 --> 00:11:40,560 problems like i remember careers advice 307 00:11:40,560 --> 00:11:42,399 at school where they'd ask questions 308 00:11:42,399 --> 00:11:44,959 like do you like being outside do you 309 00:11:44,959 --> 00:11:46,880 like people and at the end they'd say 310 00:11:46,880 --> 00:11:48,480 something like you should be a flight 311 00:11:48,480 --> 00:11:50,160 attendant or whatever and you're left 312 00:11:50,160 --> 00:11:51,040 thinking 313 00:11:51,040 --> 00:11:52,880 did they even ask the right questions 314 00:11:52,880 --> 00:11:54,079 you know what i mean the thing is there 315 00:11:54,079 --> 00:11:55,760 is actually good advice out there for 316 00:11:55,760 --> 00:11:57,519 how to find a fulfilling career it's 317 00:11:57,519 --> 00:11:59,279 just that careers advice at school 318 00:11:59,279 --> 00:12:00,880 doesn't tend to focus on that most 319 00:12:00,880 --> 00:12:02,880 importantly it's hard to find good 320 00:12:02,880 --> 00:12:04,399 careers advice for people who want to 321 00:12:04,399 --> 00:12:06,639 make a difference the advice tends to be 322 00:12:06,639 --> 00:12:09,279 follow one of these well-known career 323 00:12:09,279 --> 00:12:11,680 paths be a doctor be a teacher be a 324 00:12:11,680 --> 00:12:13,600 charity worker but those aren't the only 325 00:12:13,600 --> 00:12:15,680 options and they might not be the best 326 00:12:15,680 --> 00:12:18,399 option for you either 80 000 hours aims 327 00:12:18,399 --> 00:12:20,079 to help you find a career that's 328 00:12:20,079 --> 00:12:21,920 fulfilling and makes a big difference 329 00:12:21,920 --> 00:12:23,360 the name comes from the average length 330 00:12:23,360 --> 00:12:25,920 of a career 40 hours a week 50 weeks a 331 00:12:25,920 --> 00:12:28,320 year for 40 years their insights come 332 00:12:28,320 --> 00:12:30,800 from 10 years of research alongside 333 00:12:30,800 --> 00:12:32,720 academics at oxford university and it 334 00:12:32,720 --> 00:12:34,240 turns out the best way to make a 335 00:12:34,240 --> 00:12:36,000 positive difference might be pretty 336 00:12:36,000 --> 00:12:38,320 different to what you'd expect and you 337 00:12:38,320 --> 00:12:40,160 won't find any unsupported 338 00:12:40,160 --> 00:12:42,720 generalizations at 80 000 hours either 339 00:12:42,720 --> 00:12:44,880 like their recommendations are based on 340 00:12:44,880 --> 00:12:47,040 careful research but if they aren't sure 341 00:12:47,040 --> 00:12:49,519 about something they'll say so and to me 342 00:12:49,519 --> 00:12:51,760 that says a lot if you care about what 343 00:12:51,760 --> 00:12:54,399 the evidence says about having a 344 00:12:54,399 --> 00:12:56,800 fulfilling and impactful career and you 345 00:12:56,800 --> 00:12:59,200 want advice that goes beyond follow your 346 00:12:59,200 --> 00:13:01,680 dreams then 80 000 hours can help and by 347 00:13:01,680 --> 00:13:03,440 the way everything they provide is free 348 00:13:03,440 --> 00:13:05,360 forever because they're a non-profit 349 00:13:05,360 --> 00:13:08,560 their only aim is to help solve global 350 00:13:08,560 --> 00:13:11,120 problems by helping people like you find 351 00:13:11,120 --> 00:13:13,360 the most impactful careers they can if 352 00:13:13,360 --> 00:13:14,639 you sign up for their newsletter now 353 00:13:14,639 --> 00:13:16,639 you'll get a free copy of their in-depth 354 00:13:16,639 --> 00:13:19,360 career guide sent to your inbox you can 355 00:13:19,360 --> 00:13:21,680 go to eighty thousand hours dot org 356 00:13:21,680 --> 00:13:23,839 forward slash steve to sign up the link 357 00:13:23,839 --> 00:13:25,680 is also in the description so check out 358 00:13:25,680 --> 00:13:28,079 80 000 hours today i hope you enjoyed 359 00:13:28,079 --> 00:13:30,880 this video thanks to ulysses mendes for 360 00:13:30,880 --> 00:13:33,279 the idea if you did enjoy it consider 361 00:13:33,279 --> 00:13:35,040 subscribing and the algorithm thinks 362 00:13:35,040 --> 00:13:38,960 you'll enjoy this video next 363 00:13:38,960 --> 00:13:57,629 [Music] 26091

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