The kinetic energy of a body moving along a straight line varies with time as shown in figure. The force acting on the body:

Options

A. zero
B. constant
C. directly proportional to velocity
D. inversely proportional to velocity

Answer

B

Explanation

`(1)/(2) mv^(2) prop t`
`(1)/(2) mv^(2) = At` where `A` is constant
`v = sqrt((2A)/(m)) t^(1//2)`
`v prop = sqrtt`
`a = (dv)/(dt) = sqrt((2 A)/(m) (1)/(2 sqrtt))`
`F = ma = sqrt(2 Am). (1)/(2sqrtt)`
`F prop (1)/(v)`