Question

A car initially at rest, picks up a velocity of 72 kmh⁻¹ in 20 seconds. If the mass of the car is 1000 kg, find

1. Force developed by its engine
2. Distance covered by the car.

Answer 1

Initial velocity = u = 0
Final velocity = v = 72 kmh⁻¹
v = `72xx5/18` ms⁻¹ = 20 ms⁻¹
Mass of car = m = 1000 kg
Time = t = 20 s

1. v = u + at
20 = 0 + a (20)
(Acceleration) a = `20/20` = 1 ms⁻²
Now, F = ma
F = 1000 × 1 = 1000 N

2. Distance covered by car = S = ?
S = ut + `1/2` at²
= `0(20)+1/2(1)(20)^2`
= `0+400/2`
S = 200 m