What's the difference between torque and horsepower?
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nosbig
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Maybe but I have a 40 hp tractor that will pull way more weight than my 350 hp truck.
But it won't pull a trailer at 75 mph down the highway.
Pulling a lot of weight at low speed is all about gearing and traction.
nosbig
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But it won't pull a trailer at 75 mph down the highway.
Pulling a lot of weight at low speed is all about gearing and traction.
I thought by changing the gearing you changed torque?
You can multiply torque output, but not the torque the engine produces. Doing so reduces the rpm output. This is why your tractor can pull so much (and it's superior traction in dirt).
Torque is basically the force it takes to rotate something. It tales 19,600 in lbs of torque to keep an aluminum propeller at high pitch spinning on a turbine engine. The hp is what creates the necessary torque to do so. 5500 hp keeps the torque going to the prop
So lemme ask this... my HD makes 116lbft of tq and 110 hp. If I could get the weight down to that of a Busa. With all other things equal, what would be the comparison between the 2 bikes 0-60, 0-100 and 1/4 mile.
The Busa would win all three races because it has more hp.
Torque is force. HP is work. Work does not create force. Force with movement is work.
Work doesn't make force? So if I'm working my
off trying to push a car across a plane, then that work isn't making force?
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Shifty41
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But for most of us terms like power and work are just as ambiguous as torque and HP. Probably more so since most of us on this forum have an intrinsic instinct of how HP and torque are related and what they are. "Torque is force" doesn't mean anything if I don't know what either really means.
But anyway, like I said, I liked your example.
But anyway, like I said, I liked your example.
mysql
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If all things are equal... but not always the case. Just talk to the 600 torque trucks that have 18 gears =)
Then on the opposite side, we have F1 race cars with massive horsepower, while their torque values are much lower. They have super high rpms and can accelerate like a mad man.
My point is that you can't use absolutes in this - a diesel truck with a 200 rpm powerband is going to be vastly different than a f1 car with a really wide powerband. You can't just say torque means acceleration because there are other considerations, especially transmission and powerband.
Then we get into area under the curve situations. Peak numbers can be extremely misleading.
Force isn't required to have motion. You can push on a 3000 pound rock and have no motion but the force still exists. Work requires motion. If you and your buddies get it to move you did some work.
I'll give a similar (but not exact) example. Your two friends are having a competition pushing matching wheeled carts up an incline. Both carts weigh 500 pounds and have the same frictional losses. The first friend is a body builder and has more muscle than four normal men. The second friend is a Crossfitter and is in great shape but doesn't have the muscle the first guy does. The incline is slight, but real. Who will win the race to push the cart? When the race starts, muscle man starts pushing with a force of 450 pounds, and then the cart starts to move. Crossfitter can only manage 300 pounds of force and his cart starts to move. We know the result, because muscle man can create a larger force, right? Well, maybe. Muscle man's cart jumps out to a commanding lead and it seems Crossfit is the inferior exercise routine. Well it turns out because muscle man's legs are so large they bang together and he can only get the cart to 6 mph up the incline. At this time it only takes 120 pounds of force to keep the cart moving up the incline. Crosfitter eventually gets it up to 9 mph and passes muscle man. At this point he has to apply a force of 160 pounds to keep the cart moving. If the race was 50 feet, the muscle man wins. If it was 1/4 mile Crossfitter wins.
So does force (torque) or work (hp) win the race? The answer is neither, or both, take your pick. In the short race muscle man was able to apply his full force before the cart got going too fast so you want to say force wins the short race ... but work is measured by how far up the incline he moved the cart in a given amount of time and he did it quicker than Crossfitter so he did more work (hp). The long race was a different story because Crosfitter was able to go faster. In both cases the person who was able to exert the greatest average force (at speed) over the full distance did the most work and won the race. Forget peak numbers, you don't operate at peak except at one speed. If the incline was steep enough that they couldn't get past their peak force then muscle man wins every time, but that is rarely the case.
At any rpm the engine producing the most torque makes more hp. A real world example you can see on YouTube: Ram Ecodiesel pickup vs a Ford F150 with the 2.7 Ecoboost gas engine pulling trailers racing up a mountain. The Ram makes something like 420 lb-ft of torque and 240 hp (peak numbers!) and the Ford makes 375 and 325. From a dead stop at low rpms pulling identical trailers the Ram pulls out in front quickly. We want to say it is because of all that torque ... but wait ... it also has more hp at the low rpms as demonstrated by the distance it moves the trailer in the same amount of time (it is in front). When the Ford gets the rpm's up where it is making more hp it passes the Ram ... but it is also making more torque, even though they both are past their torque peaks as they scream near their hp peak rpms. You can argue hp or torque drives one thing or the other, but really they are mathematically related and you don't get one without the other.
I'll give a similar (but not exact) example. Your two friends are having a competition pushing matching wheeled carts up an incline. Both carts weigh 500 pounds and have the same frictional losses. The first friend is a body builder and has more muscle than four normal men. The second friend is a Crossfitter and is in great shape but doesn't have the muscle the first guy does. The incline is slight, but real. Who will win the race to push the cart? When the race starts, muscle man starts pushing with a force of 450 pounds, and then the cart starts to move. Crossfitter can only manage 300 pounds of force and his cart starts to move. We know the result, because muscle man can create a larger force, right? Well, maybe. Muscle man's cart jumps out to a commanding lead and it seems Crossfit is the inferior exercise routine. Well it turns out because muscle man's legs are so large they bang together and he can only get the cart to 6 mph up the incline. At this time it only takes 120 pounds of force to keep the cart moving up the incline. Crosfitter eventually gets it up to 9 mph and passes muscle man. At this point he has to apply a force of 160 pounds to keep the cart moving. If the race was 50 feet, the muscle man wins. If it was 1/4 mile Crossfitter wins.
So does force (torque) or work (hp) win the race? The answer is neither, or both, take your pick. In the short race muscle man was able to apply his full force before the cart got going too fast so you want to say force wins the short race ... but work is measured by how far up the incline he moved the cart in a given amount of time and he did it quicker than Crossfitter so he did more work (hp). The long race was a different story because Crosfitter was able to go faster. In both cases the person who was able to exert the greatest average force (at speed) over the full distance did the most work and won the race. Forget peak numbers, you don't operate at peak except at one speed. If the incline was steep enough that they couldn't get past their peak force then muscle man wins every time, but that is rarely the case.
At any rpm the engine producing the most torque makes more hp. A real world example you can see on YouTube: Ram Ecodiesel pickup vs a Ford F150 with the 2.7 Ecoboost gas engine pulling trailers racing up a mountain. The Ram makes something like 420 lb-ft of torque and 240 hp (peak numbers!) and the Ford makes 375 and 325. From a dead stop at low rpms pulling identical trailers the Ram pulls out in front quickly. We want to say it is because of all that torque ... but wait ... it also has more hp at the low rpms as demonstrated by the distance it moves the trailer in the same amount of time (it is in front). When the Ford gets the rpm's up where it is making more hp it passes the Ram ... but it is also making more torque, even though they both are past their torque peaks as they scream near their hp peak rpms. You can argue hp or torque drives one thing or the other, but really they are mathematically related and you don't get one without the other.
Horse power and torque are values determined by applied mathematics. Any attempt to define them otherwise is a futile attempt. See the second post.
Power = watts = N.m/sec
Torqe = N.m
Work is not hp. Work is Joules, or in imperial Btu's, again an applied math derivative.
http://www.car-videos.net/articles/horsepower_torque.asp
Power = watts = N.m/sec
Torqe = N.m
Work is not hp. Work is Joules, or in imperial Btu's, again an applied math derivative.
http://www.car-videos.net/articles/horsepower_torque.asp
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