A car of mass 1000kg accelerates uniformly from rest to a velocity of `54km//h` in 5 seconds. Calculate (i) its acceleration (ii) its gain in KE (iii) average power of the engine during this period.

Explanation

Here, `m=1000kg`
`u=0,upsilon=54km//h=(54xx1000)/(60xx60)m//s=15m//s`
`t=5s`
`a=?` gain in `K.E.=?` Average power `=?`
From `upsilon=u+at`
`15=0+axx5,a=(15)/(5)=3m//s^(2)`
Gain in `K.E.=(1)/(2)m(upsilon^(2)-u^(2))`
`=(1)/(2)xx1000(15^(2)-0)=1.125xx10^(5)J`
Average power spent
`=(W)/(t)=(ga i n i n K.E.)/(t)=(1.125xx10^(5))/(5)`
`P=22500W`