 # (a) The earth, moving around the sun in a circular orbit, is acted upon by a force and hence work must be. done on the earth by the force. State whether the statement is correct or not. Give reasons for your answer

(a) The earth, moving around the sun in a circular orbit, is acted upon by a force and hence work must be. done on the earth by the force. State whether the statement is correct or not. Give reasons for your answer.
(b) A coolie holding a heavy box is waiting at the bus stand for 15 minutes. How much work is done by him ?
© A man weighing 70 kg carries a weight of 10 kg on the top of a tower 100 m high. Calculate the work done by the man. (g = 10 m s^-2).

(a) No, work is done because the force acting on the earth and the displacement along the tangent are perpendicular to each other.
Since W = FS cos 0 and = 90°, therefore, cos 90° = 0 Hence, W = 0.
(b) Since coolie is applying force on the heavy box to hold it but there is no displacement of
the box. Therefore, work done by him is zero.
© F = (70 + 10) = 80 kg wt = 80 x 10 = 800 N
S = 100 m
W = F x S = 800 x 100 = 80000 J