Work Done by the Force of Gravity (W = mgh)

A man raises a box of mass 50 kg to a height of 2 m in 20s, while another man raises the same box to the same height in 50s. Calculated:

1. the work done, and
2. the power developed by each man. Take g = 10 N kg^-1.

What do you mean by equilibrium of a body?

State the condition when the work done by a force is positive.  Explain with the help of examples.

A force F when acts on a body, displace it by a distance d in a direction at an angle θ with the direction of the force. Write down the expression for the work done by the force.

For the following scenario, state whether the work done by gravity is positive, negative, or zero.

A car in neutral gear is coming down the slope.

A stone of mass m is rotated in a circular path with a uniform speed by tying a strong string with the help of your hand. Answer the following questions

1) Is the stone moving with a uniform or variable speed?

2) Is the stone moving with a uniform acceleration? In which direction does the acceleration act?

3) What kind of force acts on the hand and state its direction?

What happens to the power if the time for doing work is reduced from t second to t/10 second?

State two factors on which power spent by a source depends. Explain your answer with examples.