Question

. A car of mass 900kg running with a velocity of 72 km/hr is stopped at a distance of 300 m. What is the braking force

Answer 1

Mass(m) = 900kg

Initial Velocity (u) = 72km/h

[ Converting km/h to m/s we use 5/18]

So ,

Initial Velocity (u) = 72 X 5/18 = 20m/s

Final Velocity(v) = 0

Distance (s) = 300m

Acceleration (a)= ?

Using,v²-u²=2as

Substituting values we get,

0²-20²=2 X a X 300

400 = 600a

a = 400/600 = 2/3m/s²

To find the braking force, we must use the formula

F = mass X acceleration

F = 900 X 2/3F = 600N

Therefore,

600N is the braking force .