Swing Science: How Height and Weight Change Your Ride!

Before you start, ask: If I start higher, will I go faster or slower? Will I swing higher if I hold a backpack full of rocks or toys? Tell your grown-up or a friend your guesses! Scientists call these special guesses a hypothesis.

Have a grown-up pull you back just a little, then let go—how does it feel? Now try starting from the middle, and then as high as is safe. After each try, ask yourself: Did I go faster? Did I swing higher? Which was the most fun?

Now, try swinging while holding a backpack (or have a grown-up gently add some weight to your lap). Start from the same spot each time. Does it feel different with the extra weight? Do you go higher or lower? Was it harder or easier to swing? What if you add rocks or heavy toys to your backpack? Did the feeling change again?

Did your guesses match what happened? Talk about what surprised you! When you start higher on the swing, you have more potential energy, so you swing faster and go higher! A swing is one type of pendulum. Scientists have learned through lots of experiments that a pendulum will swing up to the same height it started from—unless friction or air resistance slows it down. Did you know that if you were on a swing in space, where there is almost no friction, your swing might never stop, even if you don’t pump your legs? On Earth’s playgrounds, friction takes away a little energy each time, so you slow down and eventually stop. How did it feel when you added weight? Scientists have found that adding weight to a pendulum does not make it swing faster or slower—the time it takes to swing back and forth stays the same. But changing the length of the swing does change how fast it moves! Try your experiment again on a shorter or taller swing and see what happens. Scientists use swings to learn about energy, motion, and gravity. What did you discover about swinging today?