A force of 20N is applied on a body of mass 5 kg resting on a horizontal plane. The body gains a kinetic energy of 10 after is moves a distance 2m. The fricitional force is

Options

A. 10 N
B. 15 N
C. 20 N
D. 30 N

Answer

B

Explanation

KE = `(1)/(2) mv^(2) implies 10 = (1)/(2) xx 5 xx v^(2) implies v = 2` m/s
`v^(2) = u^(2) + 2as implies a = (v^(2))/(2s) = (4)/(2 xx 2) = 1 m//s^(2)`
f = F - ma `implies 20 - 5 xx 1 = 15` N