# How to imagine the following power and torque?

I can roughly feel a force of 10 newton only by considering the weight of 1 kilogram object.

How to imagine the following measurements?

Maximum horsepower 16 hp @ 9,500 RPM

Maximum torque 12.76 N·m @ 8,500 RPM

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@John Rennie, Dungarth, torque is measured with Prony's brake. en.wikipedia.org/wiki/De_Prony_brake Such a device in action gives a rather good feeling for the torque/power in action. – Georg Jul 10 '12 at 9:19

## 3 Answers

16 horsepower is too high to be easily compared to everyday life. If you take one horsepower instead, then one horsepower is about 740 J/sec. For an average male of 75kg, this is the power required to lift you at 1 m/s. So suppose you were climbing a ladder, then 1 horsepower requires you to climb the ladder at 1 m/s. I suspect most of us could only manage a fraction of this!

The torque is more easy to imagine. A typical childs seesaw is about 2m long i.e. about 1m from the pivot to the end. If you placed a 1.276 kg weight on the end of the seesaw than 12.76Nm torque is what you'd feel at the other end when you press on the seesaw to keep it level.

The torque sounds tiny, but remember that's the torque at the motor not at the wheels. At the typical maximum speed of a small motorcycle the engine is turning about 15 times faster than the wheels, so the torque at the wheel is about 15 times as large i.e. 191Nm. That's like putting 19kg on the end of the seesaw.

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It really depends on your personal experience how you can imagine power and torque. The numbers though are very similar to a Suzuki RM 80 motocross bike.

The RM 80 has 14.5 horsepower at 11.000 rpm and a maximum torque of approximately 10 Nm at that speed.

The 'feeling' might be approximated by this video of the machine in action.

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Horsepower is a unit used to measure power, the rate at which work is executed. The SI unit of power is the watt (W) and 1 horsepower is equivalent to 746 watt. As such, you can convert 16 hp to 11 936W.

One watt is defined as 1 joule per second, joules being the SI unit of work. As work is defined by force x distance, you can get an idea of what 16hp mean by running some quick calculations.

An average car as about 1800kg of mass, and thus weighs about 18kN. This mean your 16HP motor has enough power to lift such a car 1 meters in the air in about 1.5 seconds (18kN x 1m / 1.5s = 12kW)

Torque, now, is a measure of turning force of an object. It is calculated by multiplying the force applied to the object by the distance at which it is applied to the center of rotation. Basically, if you attached a one meter stick to your motor and ran it at 8500 rpms, the force you'd feel at the end of the stick would be 12.76 Newtons, which you can easily compare to the weight of a 1.2~1.3kg object ($F=mg$, where $g$ is about 10N/kg). I would highly suggest not trying to stop it even if the force is small, however, as the end of that one meter stick would be travelling at a speed of about 3204 km/h...

Given the specs of your motor, it would be able to drag a heavier object while running at 8500 rpms (more torque) but, not as much torque was needed, it would drag it faster at 9500 rpms (more power)

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