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 frictions of the road.
D. `(mv)/(2)` exerted by the engine.

Answer

B

Explanation

Given, mass of the car =m As car starts from rest `u =0`
Velocity acquired along east `=vhati`
Duration ` =t =2s`
We know `v =u + at`
`rArr vhati = 0 + a xx 2`
`rArr 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)/(v)` is by friction Hence, force by egine is internal force .