Lyceum A - Physics - Week 14 - Friction
- Mar 1, 2022
- 3 min read
Updated: Aug 24, 2022
Friction - Friction is a force caused when one object rubs against another. It works in the opposite direction of the main force.
Gravity - Gravity is a force caused by a large body, such as the Earth. Gravity pulls objects toward the Earth.
Experiment:
For this experiment you will need a wooden spool, flat toothpick, a rubber band, tape, one large and one small metal washer and a pencil that has never been sharpened. Attach the rubber band to the middle of the toothpick by pulling one end of the rubber band through the other until it is tight around the toothpick. Thread the toothpick and rubber band through the center of the wooden spool, making sure the toothpick lays across the end of the spool. Cut or break the ends of the toothpick so they do not go past the edge of the spool. Tape the toothpick in place. Next, place the other end of the rubber band through the large washer and then the small one, sliding the pencil through at the end. Spin the pencil to wind the rubber band, then set the spool on the floor and let it go. Explain to your students that kinetic energy will send the spool racing across the floor.
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We are going to make a machine that will take up energy produced and store it and then use that stored energy to roll back to the starting point.
Experiment:
The rubber band is twisted up as the coffee can is rolled across the floor, because gravity holds the weight (a battery) in place, instead of allowing it to turn.
When friction stops the can, the energy in the twisted rubber band sends the machine back to its starting point.
Use a plank of wood or book set on an incline to allow the can to roll down the incline to build up energy.
Another version:
How to Build a "Comeback Can" Using Kinetic Energy - Mr. Wizard's Supermarket Science - 2.29 min
Experiment:
Need: A foam ball that can be held in one hand and a marble.
Place a cookie sheet on the floor next to a chair.
Stand on the chair holding the ball in one hand and the marble in the other. Hold your hands as high as you can above the cookie sheet (but both hands at the same height)
Open both hands at the same time and release the ball and marble.
Listen for the sound of them hitting the cookie sheet.
Does one land first? Or do both land at the same time?
Game - Beat Gravity:
Try to battle the pull of gravity by keeping an inflated balloon from falling to the ground.
Experiment:
This experiment is all about what factors change the affect of friction and gravity on the distance and speed an object can travel down an incline.
Try different lengths of incline plank, different angles of the incline and types of material the object will roll across to see which produces a greater distance.
Try different objects to see how weight of an object makes a difference in how much distance it will travel. Does size of the object make a difference in how far a distance it will travel?
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Videos:
Defining Gravity: Crash Course Kids #4.1 - 3.11 min
Down to Earth: Crash Course Kids #4.2 - 2.58 min
The Great Escape: Crash Course Kids #13.1 - 3.59 min
Over (to) The Moon: Crash Course Kids #13.2 - 3:54 min
Danger! Falling Objects: Crash Course Kids #32.1 - 3:32min
Introduction to Gravity - 15:46 min
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