Question

State with reasons and examples whether the following statements are true or false a particle in one dimensional motion 1.with zero speed may have non-zero velocity 2. With constant speed must have zero acceleration

Answer 1

Dear Student,
Speed is the magnitude of velocity. If the speed is zero then its velocity must be zero. Ex: A body moving moving with certain speed along x-direction stops. After stopping its speed becomes zero. Since the body is no more moving its velocity must also be zero. However, the converse is not always true.

If in a one dimensional motion the speed is constant,its velocity is also constant. Acceleration is rate of change of velocity. Since the change in velocity is zero, acceleration must also be zero. Ex: A body moving along positive x- direction with a constant speed will also have a constant velocity and hence its acceleration is zero. However, it is not true for motion along two or higher dimensions like circular motion.