Kinetic energy:

Energy that a body has when it is in motion.

Kinetic energy KE = \frac{1}{2} mv^2 . where, m - mass of the body and v - body velocity.

The kinetic energy formula is used to measure the body's mass, velocity, or kinetic energy if any of the other two numerics is given.

Step 1: Using the kinetic energy formula, calculate the object's mass.

Given that

Speed of the tennis ball, v=10m/s

Kinetic energy of the tennis ball, KE=200000 joules

KE = \frac{1}{2} m v^2     

\therefore Mass m = \frac{2KE}{v^2}

m = \frac{2 * 200000 J}{(10 m/s)^2}

m = 4000

Therefore, mass of the car m = 4000 kg