Question

An 18, 000 kg semi containing Lex Luthor in the process of stealing forty cakes is moving with a speed of 15 m/s . If Superman is to stop the van in 0.5 seconds, what force must he exert on the van?

Answer 1

540000 Newtons

Step-by-step explanation:

F = m*a

Acceleration =
`(Change in Velocity)/(time)`

The van is originally travelling at 15m/s, if superman stops the car, then it ends with a velocity of 0m/s, and he does this in 0.5 seconds. Therefore the acceleration of superman stopping the van is
`(0m/s - 15m/s)/(0.5s) = -30m/s^2` (Final velocity - initial velocity) / Time

Mass of van is 18,000 kg.

Force = 18,000 kg * -30m/s^2

Note that force is scalar, so it is always positive regardless of the sign of acceleration.

540000 N