Kinetic Energy when the Force is Perpendicular to Velocity

[Vavi Ask]

Homework Statement

Given, force of constant magnitude, which is always perpendicular to the velocity of the particle & the motion takes place in a plane. What happens to its kinetic energy? Explain.

Homework Equations

Work energy theorem

The Attempt at a Solution

According to work energy theorem, the work done turns out to be zero. This implies that the change in kinetic energy is zero i.e. the kinetic energy is constant.

 

[Clever Penguin]

Yes, this is completely correct. The change in kinetic energy is zero.

 

[Vavi Ask]

Yes, this is completely correct. The change in kinetic energy is zero.

But there is a problem. Can we answer this question in other words where this work energy theorem is not used?

 

[cnh1995]

But there is a problem. Can we answer this question in other words where this work energy theorem is not used?

Since force is perpendicular to the velocity, it has no component along the direction of the velocity vector. This means the force can't change the magnitude of the velocity. Hence, it remains constant.

 

[Vavi Ask]

Since force is perpendicular to the velocity, it has no component along the direction of the velocity vector. This means the force can't change the magnitude of the velocity. Hence, it remains constant.

Thanks a lot sir.