If a football quarterback runs into and tackles another player by grabbing onto them, what type of collision would this technically be?
a. Elastic
b. Inelastic

Which of the following would be an example of a closed system?

a. A person pushing a refrigerator box across a rough floor
b. A water bucket being pulled up by rope from a well
c. A rolling oil drum across a smooth, frictionless marble floor
d. A large moving rock slowing down while ploughing through loose sand