List of top Physics Questions on Common forces in mechanics

A uniform rod of mass 20 kg and length 5 m leans against a smooth vertical wall making an angle of \(60^\circ\) with it. The other end rests on a rough horizontal floor. The friction force that the floor exerts on the rod is (take \(g = 10\) m/s\(^2\)):

A bob of mass 0.1 \(\text {kg}\) hung from the ceiling of a room by a string 2 \(\text m\) long is set into oscillation. The speed of the bob at its mean position is 1 \(\text m\,\text s^{-1}\). What is the trajectory of the bob if the string is cut when the bob is 

1. at one of its extreme positions, 
2. at its mean position.

A truck starts from rest and accelerates uniformly at 2.0 \(ms^{-2}\). At t = 10 s, a stone is dropped by a person standing on the top of the truck (6 m high from the ground). What are the 

1. velocity, and 
2. acceleration of the stone at t = 11s ? 
   (Neglect air resistance.)

A body of mass 0.40 kg moving initially with a constant speed of 10 m s-1 to the north is subject to a constant force of 8.0 N directed towards the south for 30 s. Take the instant the force is applied to be t = 0, the position of the body at that time to be x = 0, and predict its position at t = –5 s, 25 s, 100 s.

Two bodies of masses 10 kg and 20 kg respectively kept on a smooth, horizontal surface are tied to the ends of a light string. A horizontal force F = 600 N is applied to

1. A
2. B along the direction of string. What is the tension in the string in each case?

Two masses 8 kg and 12 kg are connected at the two ends of a light inextensible string that goes over a frictionless pulley. Find the acceleration of the masses, and the tension in the string when the masses are released.