Instructions: select all the correct answers.
a free-falling golf ball strikes the ground and exerts a force on it. which sentences are true about this situation?
1. a golf ball striking the ground is a collision.
2. the ground exerts an equal force on the golf ball.
3. the ground doesn’t exert a force on the golf ball.
4. the force is zero because the golf ball has little mass.

(a) assume the equation x = at^3 + bt describes the motion of a particular object, with x having the dimension of length and t having the dimension of time. determine the dimensions of the constants a and b. (use the following as necessary: l and t, where l is the unit of length and t is the unit of time.) (b) determine the dimensions of the derivative dx/dt = 3at^2 + b. (use the following as necessary: l and t, where l is the unit of length and t is the unit of time.)