   
Seibun Mind-Development® Activities
LAB 4 – Newton’s Third Law of Motion
Equal and Opposite Forces
Information
Sir Isaac Newton developed three laws of motion. The Newton’s Third Law of Motion states for every force there is an equal and opposite force.
This law may be a little confusing when the ideas and understanding of force and mass are mixed up. The same force acting on two different objects may cause a DIFFERENT CHANGE in the motion of each object. If one object is
big the change in its motion is small. If one object is small, the change in its motion is large. Remember Newton’s Second Law of Motion, the bigger the mass the smaller the acceleration caused by a force.
When two objects bump into each other each has receives the same force, but the mass or size of the objects will cause a difference in the acceleration. An example is a crash
between two cars. When two cars crash, both cars experience the same force. The force will change motion or accelerate the cars. However the bigger car will accelerate less than the smaller car.
Equipment:
Seibun Hovercraft, smooth surface Rectangular cookie sheet and water works well Balloon or plastic sandwich bag Rubber band, water
Procedure
1. Find a smooth and level surface. Filling a large, rectangular cookie pan with water
works well for a very level and smooth surface. 2. Turn on the Hovercraft then place it
on the smooth surface. 3. Try the Hovercraft out and observe the direction the Hovercraft
moves. 4. Adjust the fan so the Hovercraft moves forward in a straight line.
5. Blow up a balloon or plastic sandwich bag (if using a sandwich bag, make sure it is blown up so the sides stick out when the bag is sealed). Wrap the
rubber band around the end of the balloon (do NOT tie the balloon closed). 6. Place the
balloon or blown up bag at one end of the smooth surface (do not hold the balloon, just set it down). 7.
Start the Hovercraft and have it move and bump into the balloon. 8. What happens
when the heavy Hovercraft hits the light balloon? 9. Open the balloon or bag. Put a
little bit of water into the balloon or bag then blow up the balloon or bag to the same size as before. 10.
Place the balloon or blown up bag at one end of the smooth surface (do not hold the balloon, just set it down). 11.
Start the Hovercraft and have it move and bump into the balloon. 12. What happens when
the heavy Hovercraft hits the balloon? 13. Repeat the testing and keep adding more and more
water until the balloon or bag is completely full. Conclusion
1. Draw and explain what happened when the Hovercraft hit the empty balloon or bag.
2. Draw and explain what happened when the Hovercraft hit the balloon or bag when both felt like they weighed the same.
3. Draw and explain what happened when the Hovercraft hit the full balloon or bag. 4.
Try to use Newton’s three laws of motions to explain what was observed while experimenting with the Hovercraft and balloon. |
