A body of mass 4 kg is accelerated up by a constant force, travels a distance of 5 m in the first second and a distance of 2m in the third second. The force acting on the body is

Options

A. 6 N
B. 8 N
C. 2 N
D. 4 N

Answer

A

Explanation

Since, distances is decreasing with time. It is retardation
`S_(1) = u - (1)/(2)a(2-1) = 5" "……(i)`
`S_(3) = u - (1)/(2) a(6-1) = 2 " "………..(ii)`
By solving (i) and (ii)
`a= (3)/(2) m//s^(2)`
Force (F) ` = ma = 4 xx (3)/(2) = 6N.`