Learning standards covered by this activity:
Major Understanding
- 5.1i According to Newton’s First Law, the inertia of an object is directly proportional to its mass. An object remains at rest or moves with constant velocity, unless acted upon by an unbalanced force.
- 5.1q According to Newton’s Third Law, forces occur in action/reaction pairs. When one object exerts a force on a second, the second exerts a force on the first that is equal in magnitude and opposite in direction.
The above learning standards were taken from the Core Curriculum Physical Setting/Physics, The University of the State of New York, The State Education Department.
Materials
- Glass root beer bottles
- Dollar bill or piece of paper cut into the size of a dollar bill
Procedure
- Place a root beer bottle on the top of a table right side up.
- Place a dollar bill on the lip of the bottle
- Place another root beer bottle on top of the dollar bill upside down
- Pull the dollar bill about 2 cm from the edge of the lips of the root beer bottles.
- With your left hand push the dollar towards the neck of the two bottles so that the dollar bows down a little and gives the dollar bill a little slack. See diagram:
- With your right hand karate chop the dollar bill
- With a little practice you should be able to remove the dollar bill from between the two root beer bottles leaving the root beer bottles standing one on top of the other.
Explanation/Possible Discussion Questions
1. In the space provided below, draw a picture of the two root beer bottles and the dollar bill. Draw in and list all the action reaction pairs possible for this set up.
Answer:
- The top bottle is pushing on the dollar bill, the dollar bill is pushing up on the top bottle.
- The dollar bill is pushing down on the bottom bottle, the bottom bottle is pushing up on the dollar bill.
- The bottom bottle is pushing down on the table, the table is pushing up on the bottle.
2. Try to pull the dollar bill out from between the two bottles. (Hint, pull quickly) The top bottle should stay put if you pull quick enough, explain why this happens in terms of Newton’s 1st Law.
Answer:
The top bottle is an object at rest, it tends to stay at rest unless another force acts on it. If you pull the bill with enough force, you over come the coefficient of friction and the bill and lip of the bottle separate.
Reinforcement Activities
The inertia ball shows students what an object at rest, stays at rest really means. Introduce inertia by showing two discrepant events and have students discuss possible explanations.
Have students experience a world without friction by riding on a hovercraft. They will soon learn through experience that it requires a force to start and stop an object. Help students understand Newton’s first law and distinguish between acceleration and velocity.
Related Products
- Inertia Ball - Show the surprising effect of an impulse load on a large inertial mass.
- Hovercraft - Discover the joy of Newton’s Laws with this 40″ wide hovercraft. Students can ride on a cushion of air and experience near frictionless motion. Now you can demonstrate action and reaction on a large scale, with no air track needed.
- Kick Dis Power Puck - This hovering puck gives a large scale demonstration of Newton’s Laws.
