By dropping a ball and seeing how long it takes to hit the ground or throw a ball up and time it as well
Answer:
A
Explanation: A is a example of Air resistance force, which is a contact force.
Answer:
C, weathering by the water.
Explanation:
While in the river, it scraps againsts other rocks and things, which causes it to change shape. For example be smoother and round.
Answer:
the spring constant k = 
the value for the damping constant 
Explanation:
From Hooke's Law

Thus; the spring constant k = 
The amplitude is decreasing 37% during one period of the motion


Therefore; the value for the damping constant 