9.3 Newton’s laws of motion Flashcards
Slide 1.3
What did Isaac Newton do with Galileo’s ideas?
Isaac Newton (1642-1727) developed Galileo’s ideas further and developed three laws of motion.
What did Galileo Galilei realize about why objects stop moving?
Galileo Galilei (1561-1642) realized that objects stop moving because the force of friction acts in the opposite direction to their motion.
What were Newton’s three laws of motion?
Newton developed three laws of motion, which changed the way people understood the world.
What does Newton’s First Law state about objects at rest?
According to Newton’s First Law, an object at rest will remain at rest unless it is acted upon by a force.
What does Newton’s First Law state about objects in motion?
Newton’s First Law states that an object that is moving will continue to move at the same speed in the same direction unless an unbalanced force acts upon it.
What is the tendency to resist changes in motion called?
The tendency to resist any change in motion is called an object’s inertia. The larger the mass of an object, the greater its inertia, and the harder it is to change its motion.
What causes a change in speed, direction, or state of motion?
Unbalanced forces cause a change in speed, direction or state of motion.
What are balanced forces?
Balanced forces are when the forces acting on an object are equal and opposite. If the forces are balanced, the object experiences no change in motion.
What are unbalanced forces?
Unbalanced forces are when the forces acting on an object are not equal and opposite. If the forces are unbalanced, the motion of the object changes.
How do balanced and unbalanced forces affect an object’s motion?
- If the forces on an object are balanced, the object experiences no change in motion.
- If the forces on an object are unbalanced, the motion of the object changes.
Example of unbalanced forces:
If only the force of gravity is pulling down on the book, without an equal upward force, the forces are unbalanced and the book will accelerate downwards.
Can you provide an example of balanced and unbalanced forces?
Example of balanced forces: The upward force of a table pushing on a book, and the downward force of gravity pulling on the book, are balanced forces.
Train or bus that suddenly accelerates, stops or turns, is an example of what law?
Example of Newton’s first law - an object at rest stays at rest, and an object in motion stays in motion, unless acted upon by an unbalanced force.
Car accidents
Example of Newton’s first law - an object continues in its state of rest or uniform motion unless acted upon by an external unbalanced force.
Newton’s second law of motion
An object will accelerate in the direction of an unbalanced force acting upon it. The size of this acceleration depends upon the mass of the object and the size of the force acting on it.
Larger force for heavier load
According to Newton’s second law, a larger force is needed to accelerate a heavy load than a lighter load.
Multiple forces acting
There is usually more than one force acting on an object at any one time.
Calculating net force
You have to calculate the overall (net) force that acts on an object.
Newton’s Third Law
For every action force, there is an equal and opposite reaction force.
Larger force for faster acceleration
According to Newton’s second law, a larger force is required to make something accelerate at a faster rate.
Newton’s second law
Newton’s second law means that the net force will cause the object to move and accelerate in the direction of that net force.
Example of Newton’s Third Law
When a tennis racket hits a ball, the racket applies a force to the ball, causing it to move. The ball also applies an equal and opposite force back to the racket.
Key Principle
The forces between two interacting objects are equal in size, but opposite in direction.
The acceleration an object experiences depends on the force applied and the object’s mass. EXAMPLE OF WHAT LAW?
Newton’s Second Law
