1. The First 3 Laws of Physics
Newton’s Laws
The First 3 Laws of Physics

2. I. Law #1 1. a base ball being pitched, then hitting ground
LAW OF INERTIA-An object at rest will remain at rest, while an object in motion will remain in motion, unless acted upon by an outside force.
EXAMPLES:
1. a base ball being pitched, then hitting ground
2. Question: When we jump straight up, why do we land in our footsteps rather than at a location equal to the distance the Earth moved during our jump?
Answer

3. Answer
We return to our footsteps because we are already moving along with the moving Earth, and according to Newton’s first law, we continue in that state of motion during the jump.

4. II. Law #2
The motion of an object will be determined as a result of two things: the amount of force that acts on the object, and the amount of mass the object contains.
F = MA
F = force M = mass A = acceleration
EXAMPLES:
A pitching machine applies force to a ball, and the ball accelerates to a certain speed. The same machine applies the same force to a ball with twice the mass, and the ball accelerates to half the speed of the first ball.
Question: When applied the same force, which will roll faster: a bowling ball or a marble?

5. Acceleration is directly Acceleration is inversely
Law #2 Continued
Acceleration is directly
proportional to force
Acceleration is inversely
proportional to mass

6. III. Law #3 Every action has an equal and opposite reaction. EXAMPLES:
An automobile is equipped with wheels that spin. As the wheels spin, they push the road backward. The road reacts by pushing the wheels forward. The size of the force on the road equals the size of the force on the wheels, but in opposite directions.
Question: When ice skating with your partner, why do you move backwards after pushing off her hands?

7. IV. Bottle Rockets - An Application of Newton’s Laws
Scenario A. The rocket changed direction once it had taken off. Why?
1. The rocket would have continued to go up, up, and up if not acted upon by an outside force!
2. GRAVITY acts as the outside force to bring the rocket back to the ground.
3. This is an application of Newton’s 1st Law

8. Scenario B. The rocket with 1000 ml of water went the highest. Why?
1. There was not enough force to make the heavier rockets fly.
a. Massive things are harder to move.
Remember: F=m x a. In our experiment F = 70 psi for every trial, while m and a changed.
The trials with small masses had a large acceleration and could go higher: psi = m x A
The trials with large masses had a small acceleration and did not go as high: psi= M x a
b. This is an application of Newton’s 2nd Law
c. According to this law, which rocket should have gone the highest?

9. Scenario B: The rocket with 1000 ml of water went. (Continued)
Scenario B: The rocket with 1000 ml of water went (Continued) the highest. Why?
There wasn’t enough water in the lighter rockets
a. Force of water shooting out = force of bottle going up.
b. The rockets with a smaller amount of water did not produce as much force as the rockets with larger amounts of water.
c. This is an application of Newton’s 3rd Law
d. According to this law, which rocket should have gone the highest?

10. Scenario B: The rocket with 1000 ml of water went. (Continued)
Scenario B: The rocket with 1000 ml of water went (Continued) the highest. Why?
Conclusion
a. Newton’s 2nd and 3rd law both affected the bottle rockets. b. Therefore, the rocket with 1000 ml of water went the highest.

11. The End