Question

once you have this set up, drop your elbow quickly and try to catch the coin with your hand. be careful...dont launch pennies across the room! 3. what do you observe? 4. which of newtons laws is represented in this demo?

Explanation:

For question 3: When you drop your elbow quickly, the coin tends to stay in its original position due to inertia (a property related to Newton's laws). So you would observe that the coin doesn't immediately move with the elbow at first (it may seem to 'lag' or stay in place briefly before falling due to gravity).
For question 4: Newton's first law (the law of inertia) states that an object at rest will stay at rest and an object in motion will stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force. The coin on the elbow is initially at rest. When the elbow is moved (a force is applied to the elbow), the coin, due to its inertia (wanting to stay at rest as per Newton's first law), doesn't move immediately with the elbow.

Answer:

1. The coin tends to stay in its initial position briefly (due to inertia) before falling.
2. Newton's first law (the law of inertia).