Lesson Plan - Get It!
Do you weigh yourself at home, or were you weighed in the doctor's office? What is the name of the device you stand on to be weighed? Although they look different, the items above weigh items, too. Find out how scientists use these different scales!
Scales are used in many different instances!
You can find a scale at your doctor’s office, at the grocery store, and probably even in your own home! There are different types of scales that use various mechanisms to measure the weight, mass, and force of objects. One type of scale that you may be most familiar with is the scale that is used to measure weight in pounds or kilograms. Other scales you may be familiar with are balance scales that use counterweights to determine mass (as seen in the picture below) and spring scales. Let's dig a bit deeper to understand more about how each scale can be a useful tool.
The scale found in a grocery store used to weigh a bunch of bananas is probably a spring scale. Spring scales use Newton's Law of Gravity to measure the weight of an object by calculating weight based on how much the spring stretches or compresses. For example, the total force on a spring scale when it is sitting still is zero. Gravity is the force that keeps them on the earth, pulling them in a downward direction, and the spring in the scale pushes in the upward direction. The force of gravity and the force of the spring are equal, but when you put something onto a scale, it measures the force of its gravitational pull, which is equal to its weight. When you put something onto the scale, the item's gravitational pull presses down on the spring and the change in length of the spring is used to measure weight.
Perhaps all of the information about a spring scale is new to you. Join Dr. Z to find out more about how a spring scale works!
As you observed in the video, you can make your own spring scale! However, spring scales do not always appear in the form of scales that you see at the grocery store. Spring scales can be found in many forms. Make one of your own and learn more about how a spring scale can be a great tool!
Continue on to the Got It? section to learn a bit more about gravity!