This document discusses friction and gravity. It defines friction as the force that two surfaces exert on each other when rubbing together, and identifies four types of friction: static, sliding, rolling, and fluid friction. Gravity is defined as a force that pulls objects toward each other. The document explains how mass and distance affect gravitational attraction between objects. It also discusses concepts related to gravity and motion like free fall, air resistance, terminal velocity, and projectile motion.

1. Friction and Gravity

2. Friction
A Smooth Surface? If you look at the polished surface of an aluminum alloy under a powerful microscope, you’ll find that it is actually quite rough.

3. Friction
The force that t wo surfaces exert on each other
when they rub together
A Smooth Surface? If you look at the polished surface of an aluminum alloy under a powerful microscope, you’ll find that it is actually quite rough.

4. Friction
The force that t wo surfaces exert on each other
when they rub together
The strength of the force of friction depends on 2
things
how hard the surfaces push together
the types of surfaces involved
A Smooth Surface? If you look at the polished surface of an aluminum alloy under a powerful microscope, you’ll find that it is actually quite rough.

5. Types of Friction

6. Types of Friction
Static Friction: Friction that acts on objects that
are not moving

7. Types of Friction
Static Friction: Friction that acts on objects that
are not moving
Sliding Friction: Occurs when t wo solid surfaces
slide over eachother

8. Types of Friction
Static Friction: Friction that acts on objects that
are not moving
Sliding Friction: Occurs when t wo solid surfaces
slide over eachother
Rolling Friction: When object rolls across the
surface

9. Types of Friction
Static Friction: Friction that acts on objects that
are not moving
Sliding Friction: Occurs when t wo solid surfaces
slide over eachother
Rolling Friction: When object rolls across the
surface
Fluid Friction: Water, oil, other liquids cause the
object to move easily

10. Static Friction
To make the sled move, the athlete first
has to overcome the force of static friction.
Static friction acts in the
opposite direction to the
intended motion.
Sliding Friction
Once the sled is moving, it
slides over the floor. Sliding
friction acts between the sled
and the floor in the opposite
direction to the sledʼs motion.
Rolling Friction
Rolling friction occurs when
an object rolls over a surface.
For the skateboarder, rolling
friction acts in the direction
opposite to the skateboardʼs
motion.
Fluid Friction
When an object pushes fluid
aside, friction occurs. The surfer
must overcome the fluid friction
of the water.
Static friction
Intended direction
of motion
Sliding friction
Direction of motion
Fluid friction
Direction of motion Rolling friction

11. Gravity

12. Gravity
StudyJams

13. Gravity
StudyJams
Gravity is a force that pulls objects toward each
other

14. Gravity
StudyJams
Gravity is a force that pulls objects toward each
other
Newton realized that Gravity acts everywhere in
the universe

15. Gravity
StudyJams
Gravity is a force that pulls objects toward each
other
Newton realized that Gravity acts everywhere in
the universe
The law of Universal gravitational states that
the force of gravity acts bet ween all objects in
the universe

16. Gravity Continued

17. Gravity Continued
Two factors affect the gravitational attraction
bet ween objects:
Mass
Distance

18. Gravity Continued
Two factors affect the gravitational attraction
bet ween objects:
Mass
Distance
Force also depends on the distance bet ween the
objects

19. Gravity Continued
Two factors affect the gravitational attraction
bet ween objects:
Mass
Distance
Force also depends on the distance bet ween the
objects
Mass is the measure of amount of matter, not to
be confused with weight

20. Gravity and Motion

21. Gravity and Motion
Free Fall: When an object is accelerating while its
falling

22. Gravity and Motion
Free Fall: When an object is accelerating while its
falling
Air Resistance:

23. Gravity and Motion
Free Fall: When an object is accelerating while its
falling
Air Resistance:
Terminal Velocity: is reached when the force of
air resistance equals the weight of the object

24. Gravity and Motion
Free Fall: When an object is accelerating while its
falling
Air Resistance:
Terminal Velocity: is reached when the force of
air resistance equals the weight of the object
Projectile Motion: Something thrown
horizontally