When a stone tied to a string is whirled in a circle, the work done on it by the string:

A pair of Oxen exerts a force of 140 newton while ploughing the field. The field ploughed is 15 meter long. The work done in ploughing the length of the field is:

A girl is swinging on a swing in sitting position. When the girl stands up, the period of the swing will :

Assume 'A' does 500 J of work in 'x' minutes and 'B' does 1000 J of work in 20 minutes. If the power delivered by 'A' is P1​ and 'B' is P2​ and P1​=2P2​, then 'x', in minutes is:

Which of the following is a non-contact force ?

A truck starts from rest down a hill with a constant acceleration. It achieves 400 meters in 20 seconds. If the weight of the truck is 7 tons then what will be the force acting on it?