Newton's Laws

Newton's Third Law

For every action there is an equal and opposite reaction.

Acceleration

1.) A change in velocity 2.) A measurement of how quickly an object is changing speed, direction or both

Velocity

The rate of change of a position along a straight line with respect to time

Newton's Laws of Motion

1. An object in motion tends to stay in motion and an object at rest tends to stay at rest unless acted upon by an unbalanced force. 2. Force equals mass times acceleration (F = ma). 3. For every action there is an equal and opposite reaction.

Unbalanced forces: Examples from Real Life

1.) A soccer ball is sitting at rest. It takes an unbalanced force of a kick to change its motion. 2.) Two teams are playing tug of war. They are both exerting equal force on the rope in opposite directions. This balanced force results in no change of motion.

If objects in motion tend to stay in motion, why don't moving objects keep moving forever?

1.)Things don't keep moving forever because there's almost always an unbalanced force acting upon it. 2.)A book sliding across a table slows down and stops because of the force of friction. 3.)If you throw a ball upwards it will eventually slow down and fall because of the force of gravity.

Newton's First Law

An object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted upon by an unbalanced force.

What does F = ma say?

F = ma basically means that the force of an object comes from its mass and its acceleration. - F = ma basically means that the force of an object comes from its mass and its acceleration. - Something very small (low mass) that's changing speed very quickly (high acceleration), like a bullet, can still have a great force. Something very small changing speed very slowly will have a very weak force.

Newton's First Law: Deeper Meaning

Basically, an object will "keep doing what it was doing" unless acted on by an unbalanced force. If the object was sitting still, it will remain stationary. If it was moving at a constant velocity, it will keep moving. It takes force to change the motion of an object.

Newton's Third Law: What does this mean?

For every force acting on an object, there is an equal force acting in the opposite direction. Right now, gravity is pulling you down in your seat, but Newton's Third Law says your seat is pushing up against you with equal force. This is why you are not moving. There is a balanced force acting on you- gravity pulling down, your seat pushing up.

Newton's Second Law

Force equals mass times acceleration. F = ma Acceleration: a measurement of how quickly an object is changing speed.

What does F = ma mean?

Force is directly proportional to mass and acceleration. Imagine a ball of a certain mass moving at a certain acceleration. This ball has a certain force.

What is meant by unbalanced force?

If the forces on an object are equal and opposite, they are said to be balanced, and the object experiences no change in motion. If they are not equal and opposite, then the forces are unbalanced and the motion of the object changes.

Newton's First Law is also called the Law of Inertia

Inertia: the tendency of an object to resist changes in its state of motion The First Law states that all objects have inertia. The more mass an object has, the more inertia it has (and the harder it is to change its motion).

Examples of F = ma

Now imagine we make the ball twice as big (double the mass) but keep the acceleration constant. F = ma says that this new ball has twice the force of the old ball. Now imagine the original ball moving at twice the original acceleration. F = ma says that the ball will again have twice the force of the ball at the original acceleration.

Force

strength or energy