Gravity - A Weighty Matter
The weight of an object makes it easier or more difficult to move. Heavier objects require more force than lighter ones to overcome gravity.
For example, have you ever picked up a kitten and then lifted a larger cat? Did you notice that you used more force to lift the larger cat? Gravity makes it more difficult to lift heavy things.
Look at the following pictures. Predict which objects require more force to overcome gravity.
Which is the heavier object of each pair? Click the object of each pair you think requires the most force to overcome gravity.
List the objects in order from lightest to heaviest.
Highlight the box below to see how many you got right!
|Marshmallows, Soda, Brick, Backpack, Milk, Bowling Ball|
With help from a parent or guardian, find four containers of food that weigh approximately one, two, five, and ten pounds. Suggestions: You might find bags or boxes of sugar, potatoes, rice, beans, pasta, or other foods that are these weights.
Now lift each box or bag separately starting with one pound and working up to ten pounds. Did you notice that you had to use more force to lift the heavier objects than you did lifting the lighter ones?
Fill in the chart below. List each item from your test in order from lightest to heaviest. Complete the chart below to record your findings.
bag of marshmallows
|one pound||very easy||
Weigh It Yourself!
Here is an activity for you to do. You can make a spring scale at home and weigh different objects. (Instructions to make this scale come from the Utah Core Academy.)
- Duct tape
- Large paper clip
- Centimeter ruler
- Various objects to be weighed
- Tape the pencil to a table, so half of the pencil is hanging over the edge.
- Hang the rubber band on the pencil.
- Open the paper clip so it looks like an "S."
- Attach the small loop of the "S" to the rubber band.
- Compare the weight of different objects by hanging them from the large loop of the "S" in the paper clip. Observe and measure the length of the rubber band with each object.
- Record your data in a table like the one below.
|Weighing With a Spring Scale|
Length of rubber band in centimeters
Now place the objects you weighed in order from lightest to heaviest. Compare your results with what your friend measures!
Look at the pictures of the SUV and the semi-truck. The SUV weighs 200 grams. The semi weighs 400 grams. Which of these requires more force to overcome gravity and move up a hill? Watch the QuickTime SUV video and Semi video to see!
Which needed more force to go up the hill? Click your choice!