Question

The force required to stop a car of mass 800 kg moving at a speed of 20 m/s over a distance of 25 m in 2.5 seconds is: a) 1200 N b) 6400 N c) 1600 N d) 1800 N

Answer 1

To calculate the force required to stop a car, we can use the equation:

Force = (mass * change in velocity) / time

Given:

Mass of the car = 800 kg

Initial velocity = 20 m/s

Final velocity (since the car is stopping, the final velocity is 0 m/s)

Distance traveled = 25 m

Time taken = 2.5 seconds

First, we need to find the change in velocity:

Change in velocity = final velocity - initial velocity

Change in velocity = 0 m/s - 20 m/s

Change in velocity = -20 m/s

Next, we can calculate the force using the equation:

Force = (mass * change in velocity) / time

Force = (800 kg * -20 m/s) / 2.5 seconds

Force = -16000 kg·m/s / 2.5 seconds

Force = -6400 N

Therefore, the force required to stop the car is 6400 N. Option b) 6400 N is the correct answer.