1. Third Grade Science Unit
Changes in Motion
Third Grade Science Unit

2. What is motion?
Motion is the change in the position of an object.

3. Motion happens when objects change position.

4. Motion is described in terms of…
Speed
Direction
Distance

5. Changes in motion…
Changes of motion are related to the mass of an object and the strength of the force acting on an object.
Mass is a measure of the number of atoms in an object combined with the density of those atoms.
You can tell how much mass something has by measuring how hard it is to get that thing to move, change directions or slow down.

6. What is a force?
Forces can start, stop or change the motion of an object. A force is necessary to change the motion of an object.

7. An object at rest will stay at rest until a force acts upon it….

8. Did you know….
An object in motion in a straight line will continue to move in a straight line at the same speed until a force acts upon it.

9. Forces are pushes and pulls

10. To increase speed add force!
Push or pull the ball to increase the speed of the ball.

11. Some ways a push or pull can change the way an object moves…
A push or pull can change the direction of an object.
A push or pull can slow down an object.
A push or pull can speed up an object.
A push or pull can stop an object.
A push or pull can start an object.

12. Gravity and Friction are forces and affect our lives….

13. What is gravity?
The force of gravity pulls objects towards earth.

14. An example of gravity: When a baseball travels in a curved path and then falls to the earth.

15. Gravity is a force that can keep objects at rest
Gravity is a force that can keep objects at rest. For example, gravity will keep objects on a table by pushing down on the object on the table. The table is pushing up on the object with equal force.
To move the object you will need to push or pull the object from the table, or remove the table from under the object.

16. What is friction?
If you’ve ever been really cold and rubbed your hands together quickly to warm up, you’ve felt friction.  You actually experience friction all the time!  Whenever any two objects rub together there is a force that makes them not glide smoothly.  This force is friction, and it’s a good thing friction exists! Otherwise, every time we took a step we would slip, slide and not stop!
Friction can either help or hinder motion.