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. . Lesson 3.1 Newton's Second Law. The net force acting on an object causes the object to accelerate in the direction of the force.F=ma. . . . F. m. a. Example:. Throw a softball (.2kg) and a baseball (.14 kg) both with a force of 40N. Do they accelerate at the same rate?. . . . Softballa=F/ma
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1. Chapter 3 Forces
2. Lesson 3.1Newton’s Second Law The net force acting on an object causes the object to accelerate in the direction of the force.
F=ma
4. Example: Throw a softball (.2kg) and a baseball (.14 kg) both with a force of 40N. Do they accelerate at the same rate?
6. Friction The force that opposes motion between two surfaces.
Depends on…
Kind of surface
Forces pushing them together
7. 3 Types of Friction Static friction- When two surfaces are not moving past each other.
Such as when you push a box and it won’t move.
8. 2. Sliding friction- When two surfaces are moving past each other.
Such as a box being pushed across the floor will move as long as there is a continuous pushing force applied.
9. 3. Rolling Friction- When a rolling object moves past a surface.
Such as a train on tracks.
A continuous force is not necessary.
10. Air Resistance Acts in the opposite direction of the motion of the object.
Throw a ball forward, air resistance is backward.
11. Lesson 3.2Gravity Anything that has mass is attracted by the force of gravity.
You to your pencil, you to the ground, your pencil to your book.
12. Law of Gravitation Any two masses exert attractive forces on each other…this attraction depends on…
Masses of the objects
Distances between them
14. Gravity and You Generally, the larger the planet, the larger the force of gravity, therefore the more you weigh.
15. Projectiles Anything shot or thrown through the air. Always flow in a curved path.
16. Centripetal Acceleration Acceleration toward the center of a curved path because of the centripetal force.
17. Lesson 3.3Newton’s 3rd Law of Motion For every action force, there is an equal in size and opposite in direction reaction force.
18. Action/reaction Pairs Always act on different objects.
A swimmer in the water:action force on the water, reaction force on the swimmer.
19. Momentum
20. Momentum Since velocity has direction, momentum has direction.
Momentum can be transferred from one object to another, but not lost nor gained…
(conservation of momentum)
21. Momentum Example: