The kinetic energy of a body decreases by 36% the decrease in its momentum is

Options

A. ` 36 %`
B. ` 20 % `
C. ` 8 %`
D. ` 6 %`

Answer

B

Explanation

` P = sqrt( 2mE) therefore P prop sqrtE `
In given problem K.E. becomes 64% of the original value.
` (P_2)/(P_1) = sqrt(( E_2)/(E_1)) = sqrt(( 64E)/( 100E )) = 0.8 rArr P_2 =0. 8 P `
` therefore P_2 = 80 % ` of the original value .
i.e. decrease in momentum is 20%