Work done by a force on a body is an example of ______
a) Mechanical work
b) Electrical work
c) Magnetic work
d) Thermodynamic work

Explanation

Hardest brake indicates that maximum force of friction is developed between car's tyre and road.
Maximum frictioN/Al force `=muR`
From the free body diagram,
`R-mgcostheta=0`
`rarr R=mg costheta`……..i
`and muR+ma-mgsintheta=0` ………ii
`rarr mu mg cos theta+ma-mg sin theta=0`

`rarr mg cos theta +a-10xx(1/2)=0`
`rarr a=5-[1-2sqrt3]xx10(sqrt3/2)`
`=5-2.5=2.5m/s^2`
`S=12.8 m/s^2 `
`u=6 m/s, velocity at the end of incline
`v=sqrt(u^2+2as)`
`=sqsrt(6^2+2(2.5)(12.8))`
`=sqrt(36+64)
`=10 m/s=36 km/hr
Hence, the harder the driver applies the brakes,m the lower will be the velocity of the cr when it reaches the ground i.e. at `36 km/hr`.