The force required to stop a car of mass 800 kg moving at speed of 20 m/sec over distance  of 25 m in 2.5 sec is

To solve this problem, we need to use the formula for force, which is mass times acceleration (F = m*a). However, we don't have the acceleration directly, so we need to calculate it first.

1. Calculate the acceleration: Acceleration is the change in velocity over time. In this case, the car is going from 20 m/s to 0 m/s in 2.5 seconds. So, the acceleration (a) can be calculated as:

a = (final velocity - initial velocity) / time a = (0 m/s - 20 m/s) / 2.5 s a = -20 m/s² / 2.5 s a = -8 m/s²

The negative sign indicates that this is a deceleration, or slowing down.

2. Calculate the force: Now that we have the acceleration, we can calculate the force.

F = m * a F = 800 kg * -8 m/s² F = -6400 N

The negative sign indicates that the force is acting in the opposite direction of the motion of the car, which makes sense because it's the force required to stop the car.

So, the force required to stop the car is 6400 N.