A car weighing 500 kg working against a resistance of 500 N accelerates from rest to 20 m s. in 10 s. The work done by the engine will be (Take `g = 10 m s^(-2))`

Options

A. `1.05 xx 10^(5)J`
B. `1.0 xx 10^5 J`
C. `1.5 J`
D. `1.5 xx 10^(5)J`

Answer

B

Explanation

As `v = u + at :. 20 + 0 + a xx 10`
or `a = 2 ms^(-2)`
Force exerted by the engine,
`F = ma + f = 500 xx 2 + 500 = 1.5 xx 10^(3) N`
`s = ut + 1/2 at^2 = 0 + 1/2 xx 2(10)^(2) = 10^(2)`
`W = Fs = 1.5 xx 10^(5) J`