"Why torque and engine speed are inversely proportional"?

Answer 1

i want to explain it by taking automobile gear as an example.
let me take automobile as car.
you know that the power produced car is same for all time. this power is transmitted to the power shaft. then it is transferred to gearbox shaft, since both are mechanically coupled. in the end of gearbox shaft there is one standard gear. there is another shaft in the gear box which contains different diameter gears.
the same power is transmitted from the std. gear to any gear in the nearest shaft,irrespective of size.
you know that,
power =(2*pi*speed*torque)/60
torque = force * radius of the engaged gear
so, it the engaged gear is of less diameter, torque will be less. but power remains the same, so automatically the speed increases.
if the engaged gear is of higher diameter than the previous one, torque will increase, this causes the speed to decrease.

Answer 2

Actually, they are not, unless you specify that power is to be a constant. By the way, in order to obtain the power you must multiply the torque (in newtons-meter) by the angular speed of the engine (in radians per second). As an example, take an internal combustion engine, an in a race car. The actual curve of torque versus speed is bell shaped, meaning there is an engine speed at which the torque is a maximum. It is at that speed that you are supposed to shift gears because maximum torque delivered to the wheels implies maximum acceleration.

Answer 3

Actually, they aren't, although at typical operating speeds torque does tend to decline as speed increases. As engine speed increases, a number of factors reduce the available torque: the fuel-air mixture spends less time in the cylinder, and may not be completely burned; the intake valve(s) are not open as long, so less fuel-air mixture may enter the cylinder; friction losses increase.

Answer 4

If you have a motor turning at a fixed speed, and if you have different set of gears, then as you change the gear to increase the speed, the torque goes down.

This is because the motor (source) has only a fixed and finite amount of power. If you increase the speed, ie. increase the distance of rotational travel, something must give. That is, give you less twisting force per angular speed (revolution).

Answer 5

They are not always inverse proportional, you are generaizing too much. The third or fourth answer provides a great (yet quick) list of other factors affecting the relationship. Gear trains can change the torque, compression ratios, fuel/air mixtures, etc.. affect the output.

Answer 6

power = 2 * pie * speed * torque / 60

so as you increase speed the torque decreases & vica-versa
For a particular power output
hence the answer

Answer 7

b/c their product is equal to power of the engine, which is constant.