Two objects A and B of mass m and 4m have the same kinetic energy. What is the ratio of the magnitude of velocities of A and B?  [Pg. No. 123]

Given that both objects have the same kinetic energy,

$$\frac{1}{2}mv_A^2 = \frac{1}{2}(4m)v_B^2$$

$$v_A^2 = 4v_B^2$$

$$v_A = 2v_B$$

Therefore, the ratio of velocities of A and B is:

$$v_A : v_B = 2 : 1$$