Question

Indicate true or false in each of the following statements:
True False  For a frictionless system, mechanical energy is always conserved.
True False  Power is the rate of use of energy.
True False  Work is zero for a force at right angles to the displacement
True False  The area under a one dimensional force vesus distance curve is work.
True False  Work is always negative

Answer 1

if the system is acted upon by only conservative force (other than Frictional forces and drag forces ,etc),then its mechanical energy remains constant

so the First statement is True

Power is the rate of use of energy ------ True

Work doen is W = F*s*cos(90) = 0 J

So Work is zero for a Force at right angles to the displacement ------True

The area under a one dimensional force versus distance curve is work---True

Work never be negative ,so

Work is always negative -----Flase