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Exploring how pushes and pulls are used to start and stop motion.
Have you ever wondered why your toys don't just start moving on their own? What 'magic' power do you use to make a ball roll or a swing fly high?
Everything around us stays still unless something moves it. To make a toy move, you have to use a force. A force is simply a push or a pull. When you push a toy car away from you, you are using force to start its motion. When you pull a wagon behind you, you are also using force! Without a push or a pull, objects will just sit there forever. We can think of force as the 'starter motor' for all movement. Whether it is a tiny marble or a big heavy door, it always needs a force to get going.
1. You see your friend sitting still on a swing. 2. You place your hands on their back. 3. You give a big push forward. 4. The swing starts moving because you applied a force!
Quick Check
What are the two types of force we use to move things?
Answer
A push and a pull.
Once an object is moving, it doesn't want to stop! To make a rolling ball or a sliding toy come to a halt, you need to use force again. You can stop a moving object by pushing against it in the opposite direction. For example, if a soccer ball is rolling toward you, you put your foot in front of it. Your foot provides a force that stops the motion. Stopping is just as important as starting, and it always requires a force to happen.
1. A friend throws a soft ball to you. 2. The ball is moving through the air. 3. You reach out and grab it with both hands. 4. Your hands provide a pulling force to trap the ball and stop it from moving.
Quick Check
If a toy car is rolling toward you, what do you need to do to stop it?
Answer
You need to use a force (like a push with your hand) to stop it.
What happens if you roll a ball and it hits a wall? The wall doesn't have hands, but it still uses force! When the ball hits the wall, the wall pushes back. This force is so strong that it stops the ball from going forward. Often, the wall pushes so hard that the ball bounces off and moves in a new direction. Even though the wall stays still, it is a master at using force to stop moving objects.
1. You roll a tennis ball fast at a flat wall. 2. The ball hits the wall with a 'thud'. 3. The wall provides a force: . 4. The ball stops for a tiny second and then zooms back toward you!
What is a 'force' in science?
To start a heavy wagon moving, what must you do?
A wall can use force to stop a ball.
Review Tomorrow
Tomorrow, look around your room and find three things you can push and three things you can pull.
Practice Activity
Try rolling a ball against different things (a wall, a pillow, a shoe). Which one stops the ball the fastest?