Question

A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle, the motion of the particle takes place on a plane. It follows that:
A. Its velocity is constant
B. It moves in a straight line
C. Its kinetic energy is constant
D. Its acceleration is constant

Answer 1

In order to answer this question, first we will explain the given statement, whether one of the given options is correct, as we know that when the force is perpendicular to the velocity, then the speed remains uniform. And the speed affects the type of energy.

Complete answer:
If the force is perpendicular to the velocity of the particle always, then it is in circular motion with uniform speed.And when the speed is uniform, then the kinetic energy is constant.The property that must be transmitted to an item in order to do work on it is defined as energy.Work may plainly be done by an object that moves at a steady speed.

We will discuss a condition in which the kinetic energy is constant: assume that a body is in motion, having kinetic energy and momentum. If this body is a closed system with no outside influences, its kinetic energy and momentum will remain constant.

In some circumstances, the force itself twists so that it is always perpendicular to the net velocity - after tilting the velocity a little, the force itself turns such that it is perpendicular to the net velocity. This is the situation when driving around a roundabout with constant turns, and it is also the case for a spacecraft in circular orbit with gravity always pointing down.

Hence, the correct option is C.

Note: A perpendicular force acting on an object will only affect the direction of its velocity, not its magnitude, as it is taught. Because there is no force in the direction of its velocity, there must be no work done and consequently no change in the object's kinetic energy, according to the explanation given to me.