1. Law of Gravitation and Friction

2. Unit Standards
5.P.5A.1
Use mathematical and computational thinking to describe and predict the motion of an object (including position, direction, and speed).
5.P.5A.2
Develop and use models to explain how the amount or type of force (contact and non-contact) affects the motion of an object.
5.P.5A.3
Plan and conduct controlled scientific investigations to test the effects of balanced and unbalanced forces on the rate and direction of motion of objects.
5.P.5A.4
Analyze and interpret data to describe how a change of force, a change of mass, or friction affects the motion of an object.
5.P.5A.5
Design and test possible devices or solutions that reduce the effects of friction on the motion of an object.

3. What is gravity and friction?
If you throw a ball upward, the gravity between it and Earth will make it fall back to the ground. Without gravity, the ball would fly off Earth.

4. What is gravity and friction?
Sir Isaac Newton, after whom the unit of force is named, researched gravity in 1600’s

5. What is gravity and friction?
Newton’s Law of Universal Gravitation- every object in the universe was pulling on every other object.

6. What is gravity and friction?
Newton said that gravity depends on the masses of the two objects and the distance between them.
Increasing the mass increases the force, and increasing the distance decreases the force.

7. What is gravity and friction?
Gravity pulls on all objects together, big and small.
The gravity between small objects is weak.

8. What is gravity and friction?
Two bowling balls an inch apart will never roll together because of gravity. Their masses are too small.

9. What is gravity and friction?
The huge masses of moons, planets, and stars make their gravity powerful. The force of gravity between Earth and the moon is 200 billion billion Newtons.

10. What is gravity and friction?
Friction- the force that opposes the motion of one object moving past another.

11. What is gravity and friction?
Friction depends on the surfaces of two objects and how hard the objects are pushed together.

12. What is gravity and friction?
Smooth surfaces usually have less friction than rough surfaces. Friction increase when surfaces are pressed together with greater force.

13. What is gravity and friction?
Friction increases with the weight of the object.
When you rub your hands together, the friction between your hands slows them down and also generates heat. Heat is created whenever there is friction.

14. What is gravity and friction?
When an object moves through air, the air hits the object and slows it down. The air resistance increases with velocity while friction usually does not.

15. What is gravity and friction?
Liquids also exert resistance. This is why water can slow down a boat.

16. What is gravity and friction?
Drag forces are a result of air resistance. Broad flat surfaces have the most drag.
This is why a feather falls slower than pencil. Without air, the two would fall at the same rate.

17. What is gravity and friction?
Drag is affected by the movement of liquids and gases. This is why it is harder to paddle upstream in a boat, or to fly into the wind in an airplane.