H$)$ At $20$ seconds, what is the Kinetic Energy of the car?

At $20$ seconds the driver steps on the brake pedal so that the net force on the car is $2500N$ forward.

How much time $($After the $20$ seconds$)$ does the car take to stop?

J$)$ How far does the car travel $($After the $20$ seconds$)$ until it reaches a stop?

The man gets out of the car. Because the car is out of gas, he pushes backward on the car with a constant force of $500N.$

K$)$ What is the acceleration of the car when the man is pushing on it$?$