How does Newton's laws pertain to cheerleading?

Answer 1

Newton's first law: The person is at rest while she (I'll pretend it's a girl) is on the ground because no net force is acting on her. Then she is thrown in the air by the force of those throwing her- why does she come down? If we assumed that there was no forces acting on her, she would continue rising forever, but since she falls, there must be a force which causes her motion to change (i.e. to slow down and then reverse direction). That force is gravity. Once on the ground again, she is no longer in motion because the downward pull of gravity is balanced by the upward normal force of the ground, and the net effect is zero force.

Newton's second law: When in the air, the girl is moving initially with upward velocity, but she slows down and then starts to fall. She must be experiencing a downward force, which again is the force of gravity. You know this because she is accelerating downward, so then you can conclude that gravity is acting in a downward direction. You can work out this part with numbers if you want.

Newton's third law: Ask the throwers- do they feel anything when they throw the girl in the air? They definitely feel pressure on their arms/hands as they throw her upward, because as they exert and upward force on her, she exerts a downward force on them equal in magnitude. The harder they throw her, the more the force they feel on themselves.