A body, when acted upon by a force of 20 kgf, gets displaced by 1 m. Calculate the work done by the force, when the displacement is

(i) in the direction of force,

(ii) at an angle of 60 degree with the force, and

(iii) normal to the force where g = 10Nkg^-1

A boy of mass 40kg climbs up the stairs and reaches the roof at a height 8m in 5s. Calculate:

(i) The force of gravity acting on the boy,

(ii)The work done by him against gravity,

(iii)The power spent by the boy.

Take g = 10 ms^-2

A weight lifter lifted a load of 200 kgf to a height of 2.5 m in 5 s.

Calculate:

(i) the work done, and

(ii) the power developed by him.

Take g = 10Nkg^-1

A machine raises a load of 750N through a height of 16m in 5s. Calculate:

(i) the energy spent by the machine.

(ii) the power of the machine if it is 100% efficient.