There are two sections of solution to this problem. The first is the impulse and the second is the force.
A.) In physics, when two objects collide, there is a small interval of time when these objects are in contact with each other. The net force applied on the two objects as one system at that time is called the impulse. Its equation is
Impulse = 2mv/t, where m is the total mass of the system, v is the velocity at impact and t is the time when the objects are in contact
But first, we have to find the velocity of impact. For free-falling objects, there is a derived equation for the velocity of impact: v = √2gh, where g is equal to 9.81 m/s^2 and h is the height of fall. Thus,
v = √2(9.81)(36) = 26.58 m/s
Impulse = 2(90 kg)(26.58 m/s)/(5×10^-3 seconds)
Impulse = 956,880 Newtons
B.) According to Newton's second law of motion: F=ma, where F is the net force applied on the system, m is the mass and a is the acceleration. For free-falling objects, the acceleration is due to gravity which is equal to g=9.81 m/s^2. Thus,
F = (90kg)(9.81 m/s^2)
F = 882.9 Newtons
