Question

A Smart Car, which has a mass of 1000 kg, is going 20 m/s. When it hits the barrier, it stops at a time of 0.5 seconds. What is the force on the car?

Answer 1

The force = F = -40000 N

Explanation:

• Mass m = 1000 kg

• speed v₁ = 20 m/s

• speed v₂ = 0 m/s

• t = 0.5

We know that,

Calculating the acceleration

using the formula

a = (v₂ - v₁) / t

= 0 - 20 / 0.5

= -20 / 0.5

= -40 ms⁻²

Thus, acceleration (deceleration) = a = -40 ms⁻²

Note: negative sign gives us an idea the car is slowing down after a collision with the barrier, thus acceleration and velocity are in opposite direction.

We know that

F = ma

= 1000 × -40

= -40000 N

Thus, the force = F = -40000 N