1. Newton’s Laws
Physics 113 Goderya
Chapter(s): 5
Learning Outcomes: All

2. Force Force: It is a push or a pull.
Force has both magnitude and direction.
Force exist in a variety of situations.

3. Types of Forces
Contact Forces: Force is due to physical contact between the bodies. Example mechanical forces.
Field Force: No physical contact is necessary to experience the force. Examples are Gravitational, Electrical, Magnetic, and Nuclear Forces.

4. Mathematics as a tool for understanding physics
A New Era of Science
Mathematics as a tool for understanding physics

5. Isaac Newton (1643 - 1727) Major achievements:
Building on the results of Galileo and Kepler
Adding physics interpretations to the mathematical descriptions of astronomy by Copernicus, Galileo and Kepler
Major achievements:
Invented Calculus as a necessary tool to solve mathematical problems related to motion
Discovered the three laws of motion
Discovered the universal law of mutual gravitation

6. Mathematics as a tool for understanding physics
A New Era of Science
Mathematics as a tool for understanding physics

7. Isaac Newton (1643 - 1727) Major achievements:
Building on the results of Galileo and Kepler
Adding physics interpretations to the mathematical descriptions of astronomy by Copernicus, Galileo and Kepler
Major achievements:
Invented Calculus as a necessary tool to solve mathematical problems related to motion
Discovered the three laws of motion
Discovered the universal law of mutual gravitation

8. Newton’s Laws of Motion (1)
A body continues at rest or in uniform motion in a straight line unless acted upon by some net force.
An astronaut floating in space will continue to float forever in a straight line unless some external force is accelerating him/her.

9. Newton’s Laws of Motion (2)
The acceleration a of a body is inversely proportional to its mass m, directly proportional to the net force F, and in the same direction as the net force.
a = F/m  F = m a

10. Newton’s Laws of Motion (3)
To every action, there is an equal and opposite reaction.
M = 70 kg
V = ?
The same force that is accelerating the boy forward, is accelerating the skateboard backward.
m = 1 kg
v = 7 m/s

11. The Universal Law of Gravity
Any two bodies are attracting each other through gravitation, with a force proportional to the product of their masses and inversely proportional to the square of their distance: Mm
F = - G r2
(G is the Universal constant of gravity.)

12. Gravity and Distance: The Inverse-Square Law
relates the intensity of an effect to the inverse- square of the distance from the cause
in equation form: intensity = 1/distance2
for increases in distance, there are decreases in force
even at great distances, force approaches but never reaches zero

13. Inverse-Square Law

14. Inverse-Square Law

15. Universal Gravitation
everything attracts everything else
example: Earth is round because of gravitation—all parts of Earth have been pulled in, making the surface equidistant from the center
The universe is expanding and accelerating outward.