Question

How much force is needed to stop a 1,400 kg truck pulling up to a stop light if

the truck took 4 seconds to stop and was moving at 36 m/s? If you know the answer please include the equation, it would really help me out, thank you! This is not math is is science btw.

Answer 1

Hi there!

`\large\boxed{-12,600 N}`

Recall that the equation to calculate force is:

F = m · a where m = mass, a = acceleration, and F = net force.

Since we are given the velocity, and time needed to stop, we can calculate the acceleration using the following kinematic equation:

vf = vi + at

The initial velocity is 36 m/s and the final velocity is 0 m/s, therefore:

0 = 36 + at

Move 36 to the other side and plug in the given time:

-36 = 4a

Divide both sides by -4 to find a:

-36/4 = a

a = -9 m/s².

Since the acceleration is -9 m/s² and the mass is 1400 kg, use the above force equation to solve:

F = -9 × 1400 = -12600 N. (negative refers to the force working in the opposite direction of the car's travel. If simply needing the magnitude of the force, it would be 12600 N)