1. 1
Newton's
Laws of
Motion

2. Newton’s First Law

3. Newton’s First Law (cont)v v v v
An object at rest tends to remain at rest and an object in motion tends to remain in motion in a straight line at constant speed,
unless acted upon by an unbalanced (net) force.
This tendency not to change velocity is called
The measure of an object’s inertia is called

4. Net Force v F4 F1 F2
F3 = Fg

5. Examples of Inertia

6. Newton’s Second Law

7. Newton’s Second Law (cont)
Fnet v1 v2 v3

8. Force of Gravity - WeightFs

9. Force of Gravity (continued)
How is it that a 2 kg mass doesn’t fall with twice the acceleration of a 1 kg mass? It is twice as massive!
In the absence of air resistance all masses fall with the same acceleration. How is this possible? 2m m Fg
2Fg

10. Newton’s Third Law F1 F2 F1 = force of girl on wall
F2 = force of wall on girl
F1 = - F2 F2 F1

11. Sample Problem 1
A fully clothed boy stands in the middle of a frozen pond. There is 0 friction between the boy and the surface of the pond. Use Newton’s Laws to explain how the boy can get to the bank of the pond with no external help (force). m2 m1

12. A 100 kg boy and a 50 kg girl stand on a frictionless frozen lake 6
A 100 kg boy and a 50 kg girl stand on a frictionless frozen lake 6.0 m apart. They each hold the end of a massless rope. The boy pulls on the rope with a force of FG and continues to exert the force until they meet. The girl holds on to her end of the rope at all times. a) With what force does the girl pull on the boy? b) What is the acceleration of the girl compared to the boy? c) How far does the boy travel? d) The girl? mB
6.0 m mG FG

13. Explain the Picture

14. Explain the Picture (cont)