chapter 5 newton’s laws of motion dr. haykel abdelhamid elabidi 1 st week of november 2013/dhh/muh...
TRANSCRIPT
Chapter 5Newton’s laws of motion
Dr. Haykel Abdelhamid Elabidi
1st week of November 2013/DhH/Muh 1434
Units of Chapter 5
• Force and mass
• Newton’s first law of motion
• Newton’s second law of motion
• Newton’s third law of motion
• Contact force
Force and mass
• A force is a push or a pull.
• The force is a vector (defined by its magnitude and its direction).
• The mass of an object is a measure of how difficult it is to change its velocity: It is more difficult to stop a car than to stop a baseball.
• The mass can also be defined as the measure of the quantity of matter in an object.
Newton’s first law of motion
• An object at rest reamains at rest as long as no net force acts on it
• An object moving with constant velocity continues to move with the same velocity (same speed and direction) as long as no net force acts on it.
• In order to change the velocity of an object –magnitude or direction – a net force is required.
If the net force on an object is zero, its velocity is constant.
Newton’s second law of motion
• Acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
• Acceleration is inversely proportional to mass• Acceleration is proportional to force
These observation give: or
If an object have several forces acting on it; the acceleration is due to the net force (sum of force vectors):
The force is a vector, we can find its components:
Newton’s second law of motion
Exercise 5-1 p116:
Newton’s third law of motion
when two bodies interact, the force which body "A“ exerts on body "B" (the action force ) is equal in magnitude and opposite in direction to the force which body "B" exerts on body "A" (the reaction force). (the law of action-reaction)
Weight and normal force
Newton’s laws of motionExample 5-1 p119:
Example 5-2 p121:
Newton’s laws of motion
1 mi =1609 m
Newton’s laws of motionExample 5-3 p123:
Contact force
Thank you for your attention
See you next time Inchallah