Inclined Planes with Wheels and Axles

The longer the ramp, the less force we need.  Wheels and axles help us overcome friction.

Students used spring scales to measure the amount of force required to lift weights to a height of 1 foot.  They then measured the amount of force to drag the object up ramps of varying lengths (2, 3 or 4 feet) to reach the height of one foot.

We found that the longer the ramp, the less force we needed, but the total energy required (force X distance) was way more on the ramps.  We also measured the force to drag the weight over a flat surface.  We found when we subtracted this force from the force needed to pull the weight up the ramp, the energy required for all methods was about the same.

One group had a toy truck as their weight.  They found that their friction was near zero and that the energy needed to go up the ramps (force X distance) was about the same using all ramps and it was about the same as lifting the truck straight up.

Ramps help us raise objects by lessening the amount of force we need to apply to the object to move it, but we have to move it a greater distance.

Inclined Planes

Today we did 4 different experiments to help us better understand inclined planes and what they do.
1) Walk Up - Students walked up ramps with varying steepness to see how a steeper incline requires more effort. Students also saw that less work, required a greater distance.
2) Book Lift - Students lifted a book to feel the effort it takes to raise it. They then pulled it up an inclined plane to feel how the ramp decreased the amount of effort it takes to raise the book.
3) Ramp Up - Students pulled a book up ramps of varying steepness to feel that the increase in ramp steepness translated into increased effort.
4) Hill Racer - Students raced spools down ramps of varying steepness to see how far their "racer" would travel.
Inclined planes are simple and fun to make at home - they're ramps! Encourage the scientist or inventor in your house to experiment with inclined planes.

Levers

"With a lever long enough and a fulcrum strong enough, I could move the world."

Levers help us lift heavy objects. With a long enough lever, a very small person can lift very big things. In this experiment, students lifted Mr. Freeman. Even the smallest student was able to lift his nearly 200 pounds!