A car weighing 550 kg, ascends a hill with a gradient of 1 in 6 at a speed of 36 kmph. Find how much work is done per second, (a) in moving the car up the hill overcoming a total force of friction and air resistance equal to 350 kgwt.

Explanation

Given, m = 550 kg, `sintheta=(1)/(6),v=36xx(5)/(18)=10ms^(-1)`
`t=1s`
(i) We know that, P = fv = mav = `(mgsintheta)` v
`=(550xx9.8xx1xx10)/(6)=8.965xx10^(3)W`
(ii) Power spent in overcoming friction = `8.965xx10^(3)W`
(iii) Power spent in overcoming air friction `=(350xx9.8xx1xx10)/(6)=5.705xx10^(3)W`
`P=14.670xx10^(3)W`.