Force and Motion

Speed The distance traveled by an object divided by the time taken to travel that distance. Speed = distance/time Example: Speed = 360km/4h = 90 km/h

Example for calculating speed: What is the speed of the balloon that travels 20m in 10s? Speed = 20m/10s = 2m/s

Velocity The speed of an object in a particular direction. Example: 30m/s north

Acceleration The rate at which velocity changes. This can include a change in direction, change in speed, or both. Acceleration = (final velocity – initial velocity)/time Example: (5m/s – 1m/s)/4s = 1m/s2 south

Forces A push or pull. Net Force: all the forces acting on an object.

Net Force Forces acting in the same direction are added to determine net force. Forces acting in different directions are subtracted to determine net force.

Balanced forces Net force = 0 Newton's Will not cause a change in motion.

Unbalanced forces Net force does not equal 0 Newton’s. Causes a change in direction or starts movement.

Determine the net force What is the net force for situation A? Net force = 0 N

Determine the net force What is the net force for situation B? Net force = 5N left

Determine the net force What is the net force for situation C? Net force = 0 N

Determine the net force What is the net force for situation D? Net force = 15N upward

Friction Force that opposes motion between two surfaces that are in contact. Example: Brakes of a car, tires and the ground.

Gravity A force of attraction between objects that is due to their masses. Large mass = strong gravity. Closer together = strong gravity.

Newton’s First Law of Motion An object at rest remains at rest, and an object in motions remains in motion at constant speed and in a straight line unless acted on by an unbalanced force.

Newton’s First Law of Motion Also known as the law of inertia. Inertia is the tendency of an object to resist any change in motion. Example: When you are in a car, your body is moving. It wants to keep on moving.

Newton’s First Law of Motion Video clip

Newton’s Second Law of Motion The acceleration of an object depends on the mass of the object and the amount of force applied. Ex. Empty cart vs. full cart Ex. Small force vs. large force

Newton’s Second Law of Motion Video Clip

Newton’s Third Law of Motion Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.

Newton’s Third Law of Motion All forces act in pairs. Action and reaction forces. Example: A rocket

Newton’s Third Law of Motion Video Clip

Which Law? A magician pulls a tablecloth out from under dishes and glasses on a table without disturbing them.

Which Law? Pushing a child on a swing is easier than pushing an adult on the same swing.

Which Law? Rockets are launched into space using jet propulsion where exhaust accelerates out from the rocket and the rocket accelerates in an opposite direction.

Which Law? A soccer ball accelerates more than a bowling ball when thrown with the same force.

Which Law? A person’s body is thrown outward as a car rounds a curve on a highway.

Which Law? A rabbit’s legs exert a force on Earth. Earth exerts an equal force on the rabbit’s legs, causing the rabbit to accelerate upward.

It is……. Newton’s First Law of Motion!

It is……. Newton’s Second Law of Motion!

It is……. Newton’s Third Law of Motion!

It is….. Newton’s First Law of Motion!

It is…… Newton’s Second Law of Motion!

It is……. Newton’s Third Law of Motion! Great job!!!