If C is 1kg and D is 100kg, and the initial velocities of both balls are 5m/s, how would the magnitude of the forces exerted by each ball on the other during the collision compare?

The forces exerted by each mass is best understood in terms of their momentum.

Momentum is a sort of compelling force or impulse. It is given as:

Momentum = mass x velocity

Let us consider the momentum of the balls;

Substance C;

Mass = 1kg

Velocity = 5m/s

Momentum of C = 1 x 5 = 5kgm/s

Substance D:

Mass = 100kg

Velocity = 5m/s

Momentum of D = 100kg x 5m/s = 500kgm/s

Body D has a higher momentum compared to Body C. This suggests that body D will exert a higher force than C when they collide.

The higher the momentum, the more the force of impact it has.