A steel ball of mass 2.4 kg is tied to a string and whirled it in a horizontal plane in a circle of diameter 2 m at a constant speed of 20 rpm. The tension in the string is (ignore gravity)

31) A 10 kg Aluminium block is dragged on a plain horizontal surface at a constant velocity of 2 m/s. A frictional force of 60 N acts on it. What is the net force acting on the block?

32) A crane lifts a mass of 200 kg from rest and it attains an upward velocity of 3 m/s in 2 s uniformly. The tension in the supporting cable is

33) Two bodies m1 and m2 (m1>m2) have the same kinetic energy. Then their momentum p1 and p2 satisfy

34) The Earth, Jupiter, Saturn and Uranus all revolve around the Sun. The Earth takes 1 year, Jupiter takes 12 years, Saturn takes 30 years and Uranus takes 84 years to complete one revolution around the Sun. At what periodicity, all these four planets lineup