A boy carrying a school bag on his shoulder does no work . (Why)

When is the work done in the following situation: (i) A boy pushing a wall (ii) A girl carrying a school bag on her shoulders (iii) A stone falling freely (iv) A boy climbing up the stairs.

A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a lavelled road. The wrok done against the gracitational force will be (g=10ms^(2))

A man of mass 50 kg carries a bag of weright 40 N on his shoulder. The force with which the floor pushes up his feet will be -

A coolie carrying a load on his head and moving on a frictionless horizontal platform does no work. Explain the reason why.

How does a syringe work?

A boy goes to a school from his home at a speed of x km/hr and comes back at a speed of y km/hr, then the average speed is given by

A coolie X carrying a load on his head climbs up a slope and another coolie Y carrying the identical load on his head moves the same distance on a frictionless horizontal platform. Who does more work. Explain the reason

A man carries a load on his head through a distance of 5 m. The maximum amount of work is done when he

The boys and girls in a school are in the ratio 8 : 3 . If the number of girls is 405 ,how many boys are there in the school

Statements given below are incorrect. Write the correct statements. Q. A headmaster giving a speech in a school assembly does work.