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.

Less power is required while slowly lifting a box than while lifting it up quickly.

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

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

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

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.

A simple machine cannot reduce the work required to do a task.

Explanation / Answer

1.Less power is required while slowly lifting a box than while lifting it up quickly.

Power = Energy/time; Just by looking at the equation for power it should be obvious that to do more work per unit time (i.e. do something quickly) you need more power.

hence False

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

For a constant mass this is true. KE =0.5mV^2 so to change the velocity you need to accelerate the object and therefore an force is involved

3. 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.

Yes it is tue, as above work done is force x distance.

4. A simple machine cannot reduce the work required to do a task.

Unless the machine is powered you will still have to do the same amount of work just over a different time frame.


Reference https://www.physicsforums.com/threads/energy-work-help-with-truth-or-false.46118/

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