1. How many laws did Newton create?
Agenda
Turn in SQ3R
Newton’s Laws lab

2. What is force?
Agenda for Wednesday Oct 27th
Newton’s Laws Notes

3. Forces
Def – an action exerted on an object to change the object’s state of motion (resting or moving)
Magnitude and direction
Units: Newtons (N)
Net force – total force on an object
When there is a net force on an object, the object accelerates in the direction of the net force
If net force = 0, then the object does not move

4. Balanced forces Net force = 0, no movement Forces are balanced
An object standing still will not move
An object moving will not stop

5. Unbalanced Forces Net force is greater than zero, unbalanced force
Object will move

6. Friction
Force that opposes motion between two surfaces that are in contact
2 types
Static – friction between two forces at rest, initial friction an object must overcome
Kinetic – friction between two moving objects
Static friction is usually greater

7. Newton’s Laws He was born the same year that Galileo died
Newton had ideas about motion, which he called his three laws of motion
Also had ideas about gravity, the diffraction of light, and forces
Physics and Math
Helped create Calculus

8. What is the net force on the object below?
Agenda for Thursday Oct 28th
Finish Newton’s Laws
Force problems
Questions on page 336

9. First Law Law of inertia
An object at rest will stay at rest and an object in motion stays in motion unless acted on by an external force
Inertia – tendency of an object to stay at rest or stay in motion
Mass is a measure of inertia
Small mass = less inertia
Seatbelts

10. Second Law
The unbalanced force acting on an object equals the object’s mass times its acceleration
F=ma
Force is measured in Newtons (N)
1 N = 1 kg x 1 m/s2
Q: What is the force necessary for a 1600 kg car to accelerate forward at 2.0 m/s2 ?

11. 2nd Law Problem
Mike's car, which weighs 1,000 kg, is out of gas. Mike is trying to push the car to a gas station, and he makes the car go 0.05 m/s2 . Using Newton's Second Law, compute how much force Mike is applying to the car.

12. Third Law For every action there is an equal and opposite reaction
Opposite in direction.
Whenever an object pushes another object it gets pushed back in the opposite direction equally hard
Example: Balloon full of air being released

13. What are Newton’s 3 Laws? Agenda for Friday Oct. 29th Quiz
Go over Force Problems
Video

14. A person that weighs 50 kg runs and hits a wall with a force of 50 N
A person that weighs 50 kg runs and hits a wall with a force of 50 N. What was the person’s acceleration as they hit the wall? With what force did the wall hit the person?
Agenda For Monday Nov. 1st
Review Newton’s Laws
Lab
Questions on page 336

15. Why does a semi-truck take longer to stop than a small car?
Agenda Tuesday Nov 2nd
Momentum
Gravity

16. Momentum Def. – mass and velocity of an object
P=mv
Units: kg x m/s AND direction
Objects with larger mass have more momentum
Objects moving faster have more momentum

17. Calculate Momentum
Calculate the momentum of a 6.00 kg bowling ball moving at 10 m/s toward the pins. Calculate the momentum of the following objects: a. a 75 kg speed skater moving forward at 16 m/s b. a 135 kg ostrich running north at 16.2 m/s c. a 5.0 kg baby on a train moving east at72 m/s d. a seated 48.5 kg passenger on a train that is stopped

18. Force and Momentum To catch a ball you use a force to stop the ball
You change the ball’s momentum
If you increase the time to catch the ball you reduce the force

19. Momentum and Collisions
The total amount of momentum is an isolated system in conserved
m1v1 = m2v2
During a collision, momentum can be transferred
Hitting billiard ball

20. Cart collisions

21. Gravity
Read pages 352 – 359
Answer questions 1-6 on page 359

22. How does weight differ from mass?
Agenda for Wednesday Nov 3rd
Gravity
Energy

23. Force of Gravity
All objects in the universe attract each other through gravitational force
Mass increases – force of gravity increases
Distance increases – force of gravity decreases

24. Force of Gravity
Free fall – only force of gravity is affecting an object
Calculate the acceleration at which an object free falls
Earth – 9.8 m/s2

25. Force of Gravity Weight is not the same as mass
Depends on gravity
Different locations have different gravities and therefore different weights
Force of gravity on an object is weight
weight = mass x free fall acceleration
w=mg
Newtons (N)

26. Projectile Motion Vertical and horizontal components
No affect on each other
Combined they form a curved path
Same acceleration downward because of gravity and will land at the same time