Select which of the following statements are True or False. Assume Newtonian Mec

Question

Select which of the following statements are True or False. Assume Newtonian Mechanics.

A)A particle's kinetic energy can change without having any net work done it.

B)The work required to lift a mass one meter depends on the speed at which it is raised..

C)A simple machine may reduce the force required to do a task.

D)The work done by a constant force acting on an object is equal to the magnitude of the force times the distance the object moves.

E)The power required to lift a mass does not depend on the speed at which the mass is raised.

F)The speed of an object is same in all inertial reference frames.

Explanation / Answer

A) false

change in KE of a particle suggests change in its speed. hence the particle must be having acceleration. we know from newton's second law that acceleration is not possible in the absence of a net force. hence there must be some net force for acceleration to be present and hence net work done for kinetic energy change to be possible

B)

false

to lift the mass , a force against gravity is applied , the work done is simply the difference in potential energy of the mass at two different heights saperated by 1 m

hence speed has no role to play here

c)

True

Using pulley it is easier to lift a heavy object rather than lifting it directly.

d)

False

Work done is the dot product of force applied and the displacement made

E)

True

The work required to lift a mass does not depends on the speed at which it is raised.

Power is rate of doing work and power also doesn't depend on the speed

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