Question

Why is it easier to revolve a stone using a shorter string than a longer string ?

Answer 1

The force that can cause an object to rotate around an axis is measured in torque. In linear kinematics, force is what causes an object to accelerate. Torque is also responsible for the angular acceleration. As a result, torque can be defined as the linear force's rotational equivalent.

Complete answer:
Torque is required to rotate a system. The formula for torque is as follows:
Torque = Force $\times$ Perpendicular Distance
The length of the string is the perpendicular distance in this case. Since torque is proportional to perpendicular distance, the longer the string is, the more torque is needed to rotate it. As a result, we can deduce that attaching a stone to a shorter string makes it easier to revolve it.

Additional Information:
Torque is part of an engine's basic specification: an engine's power output is expressed as torque multiplied by the axes' rotational speed. Internal-combustion engines can only generate usable torque over a narrow range of rotational speeds.

A dynamometer may be used to calculate the varying torque output across that range and display it as a torque curve. The torque is a pseudovector in three dimensions, and it is given by the cross product of the position vector (distance vector) and the force vector for point particles.

Note: Steam engines and electric motors produce maximum torque near zero revolutions per minute, with torque decreasing as rotational speed increases (due to increasing friction and other constraints). Without a clutch, reciprocating steam engines and electric motors can start heavy loads from zero rpm.