Torque and Power

d10 · #1 02-26-2006, 04:02 PM

Inspired by the recent technical car questions here, this question was posed on a car enthusaist message board a while ago. It turns out most car enthusaists don't know the basics of how their car works. There are a lot of smart, technically minded people here, so maybe you all can do better.

You are challenged to a drag race with your choice of two cars. Both cars are identical other than their engines. One car's engine has more torque but less power than the other. The other engine has more power but less torque. Both cars are equipped with a theoretically perfect continuously variable transmission. Meaning that for any given engine RPM, an infinite range of gear ratios are available. Assume that throughout the race, the most efficient gear ratio will be selected in both cars at any given time. Do you take the car with more power, or more torque? Feel free to explain your decision.

Jimbo · #2 02-26-2006, 04:13 PM

In a short drag race more torque, in a race several miles long, more power.

Jimbo

kyro · #3 02-26-2006, 04:14 PM

I just learned how to put more oil in my car.

8Tdiamonds · #4 02-26-2006, 04:37 PM

[ QUOTE ]
Both cars are equipped with a theoretically perfect continuously variable transmission.

[/ QUOTE ]

If this were the case more hp would win the race.

man · #5 02-26-2006, 04:50 PM

I guessed torque because I always thought that it only matters how much force the wheels produce. but I am not a car enthusiast and I don't even know what the mechanical relation is between torque and power.

mostsmooth · #6 02-26-2006, 04:53 PM

i believe the correct answer is it doesnt matter which car you pick

d10 · #7 02-26-2006, 05:49 PM

There are no tricks in the question. There is one definitive answer that can be reached based on the information given. So it doesn't matter how long the race is, it doesn't matter exactly how much torque/power each car has, and one will definitely be faster than the other.

spy587 · #8 02-26-2006, 06:19 PM

I dont really remeber much of physics but here it goes.

Power=Torque*Distance/Time

Therefore, torgue is just one factror of power and it is more important to have a greater power even with crappy torque.

Jimbo · #9 02-26-2006, 06:24 PM

[ QUOTE ]
There are no tricks in the question. There is one definitive answer that can be reached based on the information given. So it doesn't matter how long the race is , it doesn't matter exactly how much torque/power each car has, and one will definitely be faster than the other.

[/ QUOTE ]

Ok given your clue I figured it out, but you are incorrect, their is a trick to your question. Shame on you for stating otherwise.

Jimbo

Razzputin · #10 02-26-2006, 07:04 PM

[ QUOTE ]
[ QUOTE ]
There are no tricks in the question. There is one definitive answer that can be reached based on the information given. So it doesn't matter how long the race is , it doesn't matter exactly how much torque/power each car has, and one will definitely be faster than the other.

[/ QUOTE ]

Ok given your clue I figured it out, but you are incorrect, their is a trick to your question. Shame on you for stating otherwise.

Jimbo

[/ QUOTE ]

I do not know much about cars but I am a physics major. If one truly has more power for the whole race and one has less torque for the whole race then one car will be faster for the whole race.
Torque is rotational force.
Power is work done over time, or Torque times the angular speed. If its power is higher and its torque is lower then its RPM has to be higher.