Answer: 1687.5 N
Explanation:
From the second law of motion given by Newton, Force is the rate change of momentum.

Mass of the baseball, m = 0.15 kg
Initial velocity,
(negative because direction of initial velocity is opposite to the final velocity)
Final velocity, 
The duration of collision, 
Force, 
Hence, the value of force is 1687.5 N.
Answer:
The SI unit of intensity is the watt per square meter/metre (W/m^2.)
Explanation:
Intensity is equal to the power transferred per unit area. Since power is measured in watts (W) and 1 W = 1 J/s, then intensity can be viewed as how fast energy goes through a certain area.
In physics, intensity is often used when studying light, sound, or other phenomena that involve waves or energy transfer. (With waves, the power value is taken as the average power transfer over the wave's period.)