The force required to make an object of mass m, travelling with velocity v, turn in a circle of radius r is

A machine gun with a mass of 5kg fires a 50g bullet at a speed of 100 ms\(^{-1}\). The recoil speed of the machine gun is 

If in a simple pendulum experiment the length of the inextensible string is increased by a factor of four, its period is increased by a factor of?

In what range of temperature is the expansion of water anomalous?

Which of the following statements about radioactivity is true?

(i) Alpha particle is positively charged

(ii) Beta particle is negatively charged

(iii) Gamma ray is neutral

(iv) Beta particle has the  same mass as helium atom

(v) Gamma ray is charged.