Question

A 9-kg body has three times the kinetic energy of an 4-kg body. Calculate the ratio of the speeds of these bodies.

Answer 1

Answer:

 speed 9/speed 4   =   2sqrt3 / 3

Explanation:

KE = 1/2 m v^2

for 9 kg   = 3 * the 4 kg      1/2 (9)va^2   = 3* 1/2 (4) vb^2

va^2 / vb^2 = 3*  1/2 (4) / (1/2 *9)

                      6 / 4.5

va / vb = sqrt (6/4.5) =  2sqrt3 /3

ratio of the 9 speed  to the speed of the 4   is  2 sqrt 3 /3