If the kinetic energy of a car travelling at 20 m/s is 200 000 J and its braking distance at that speed is 50 m what is the braking force?

To find the braking force, we first need to understand the relationship between energy, work, and force. The work-energy principle states that the work done on an object is equal to the change in its kinetic energy.

Step 1: Identify the initial kinetic energy and the final kinetic energy. In this case, the initial kinetic energy is 200,000 J (given in the problem) and the final kinetic energy is 0 J (since the car comes to a stop).

Step 2: Calculate the work done. The work done on the car to bring it to a stop is equal to the change in kinetic energy. So, the work done is initial kinetic energy - final kinetic energy = 200,000 J - 0 J = 200,000 J.

Step 3: Understand the relationship between work, force, and distance. Work is also equal to the force applied on an object times the distance over which the force is applied (Work = Force x Distance).

Step 4: Rearrange the formula to solve for force. Force = Work / Distance

Step 5: Substitute the values into the formula. Force = 200,000 J / 50 m = 4,000 N

So, the braking force is 4,000 Newtons.