Education.com
Try
Brainzy
Try
Plus

Uphill: How Does an Inclined Plane (a Flat, Sloping Surface) Make Lifting an Object Easier?

based on 4 ratings
Source:
Author: Janice VanCleave

Problem

How does an inclined plane (a flat, sloping surface) make lifting an object easier?

Materials

• Scissors
• Large rubber band
• Ruler
• 3 books
• Yardstick (meterstick)
• 1 cup of rice
• Sock
• String

Procedure

1. Make a scale as follows:
• Cut the rubber band to form one long rubber strip.
• Lay the rubber strip on a ruler. Pull the end of the strip over the edge of the ruler and tape it to the back of the ruler. Leave about 3 inches (7.6 cm) of the strip hanging down the front of the ruler.
2. Stack the books on a table.
3. Place one end of the yardstick (meterstick) on the edge of the books to form a ramp.
4. Pour the rice into the sock, and tie a knot in the sock.
5. Measure and cut a 12-inch (30-cm) piece of string.
6. Tie one end of the string to the free end of the rubber strip and the other end of the string around the top of the sock.
7. Place the sock on the surface of the table, and lift the scale straight up until the sock is at a height equal to that of the stacked books.
8. Observe the distance the rubber band stretches along the ruler.
9. Place the sock on the bottom part of the ramp.
10. Hold onto the scale, and slowly pull the sock to the top of the ramp.
11. Again observe the distance the rubber band on the scale stretches as the sock is being pulled up the ramp.

Results

The rubber band stretches a shorter distance when used to pull the sock full of rice up the ramp than when lifting the sock straight up.

Why?

The ramp is an inclined plane (a simple machine with a flat, sloping surface). It is used to move an object to a higher level with minimal effort. The length of the rubber band indicated that it took less effort force (the force you apply) to move the sock full of rice up the ramp than to lift it straight up. When using an inclined plane, you must move the object a greater distance than if you lifted it straight up, but it takes less effort force.

Let's Explore!

1. Does the slant of the ramp affect the amount of effort required to move the sock to the top? Repeat the experiment twice, first increasing the slant by adding more books to the stack, and then decreasing the slant by using fewer books.
2. Does the surface of the ramp affect the results? Repeat the original experiment twice more, first taping wax paper across the yardstick (meterstick) to provide an extra smooth surface, and then taping sandpaper across the stick to provide a rough surface. Science Fair Hint: Display the materials used with a summary of the results. In your written report about these results, include information about the difference in friction (the resistance to motion) between the rough and smooth surfaces.

Show Time!

1. Use a hand-held scale to measure the amount of force required to lift a book straight up. Form an inclined plane by placing a board on the edge of the seat of a chair. Place the book on the bottom end of the ramp, and use the scale to pull the book up the ramp. Measure the effort force needed to pull the book up the ramp. Display photographs showing the book being held by the scale, and also being pulled up the ramp by the scale. Indicate the force required to lift the book straight up and to pull it up the ramp.
2. Take a closer look at the world around you. Observe and discover common inclined planes—such as stairs, wheelchair ramps, roads winding up and around a mountain, and ramps at loading docks—used to move objects to higher levels. Photographs of different kinds of inclined planes, along with pictures from magazines, can be used as part of a project display.

Check It Out!

More than 2,000 years ago the Egyptians built tombs for the pharaohs. Some of the tombs are more than 400 feet (133 m) tall. The largest, built by the pharaoh Khufu, has at least 2,300,000 carefully cut and exactly laid stones weighing about 3,000 pounds (1,364 kg) each. Read about the pyramids and find out how the Egyptians used inclined planes to place these large stone blocks one on top of the other.