A car of mass m starts from rest and acquires a velocity along east `upsilon = upsilonhati (upsilon gt 0)` in two seconds Assuming the car moves with unifrom acceleration the force exerted on the car is .

Options

A. `(mv)/(2)` eastward and is exerted by the car engine
B. `(mv)/(2)` eastward and is due to the friction on the tyres exerted by the road
C. more than `(mv)/(2)` eastward exerted due to the engine and overcomes the friction of the road
D. `(mv)/(2)` exerted by the engine

Answer

B

Explanation

(b)Given, mass of the car=m
As car starts from rest,u=0
Velocity acquired along east`=v_(i)`
Duration=t=2s
We know that, v=u+at` implies vhati=0+axx2`
`implies" "a=(v)/(2) hati`
Force, `" " F=ma=(mv)/(2) hati`
Hence, force acting on the car is` (mv)/(2) ` towards east. As external force on the system is only friction hence, the force `(mv)/(2)` is by friction. Hence, force by engine is internal force.