Chapter 10 Forces

Force and Net Force Force is a push or a pull on an object. Net force is the total force on an object.

Unbalanced Force Balanced Force The balanced forces are the forces in equal and opposite directions. Unbalanced Force can cause an object to move, stop moving, or change direction.

Forces change motion.

HMM…. Can you see the unbalanced force here?

Newton’s First Law Inertia An object at rest will stay at rest unless acted upon by an outside force. Inertia is every objects resistance to change its motion. Greater mass means Greater inertia

Take out a piece of paper and label it “Inertia Mini Lab”

Newton’s Second Law The acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to the object’s mass.

Force=mass x acceleration F=m x a Or a = Force/ mass a = F/m

Equation for Newton It’s the same as the force equation! Newton=m x a.

Force and mass determine acceleration.

Luke! Use the mass times the acceleration!

Sometimes we might calculate mass using Force and Acceleration Mass=Force/Acceleration m=F/a

How much Force was required to make a 2000kg car accelerate at 5m/s/s? 400N 0.001N 10,000N Force=Mass x acceleration F=ma F=2000kg x 5m/s/s a= 10,000N or kgxm/s/s

If you drop a 15kg bowling ball with a Force of 147N, what is it’s acceleration? 30 9.8m/s/s 0.1m/s/s 2,205m/s/s Acceleration=Force/Mass a=F/m a=147kgxm/s/s÷15kg a= 9.8m/s/s

A person throws a baseball at an acceleration of 25m/s/s with 12 A person throws a baseball at an acceleration of 25m/s/s with 12.5N of Force. What’s the Mass of the ball? 312kg .5kg 2kg Mass=Force/Acceleration m=F/a a=12.5kgxm/s/s÷25m/s/s a= .5kg

Friction

4 Types of Friction The 4 types of friction are: Sliding friction (strongest) Rolling friction Fluid friction (weakest). Static friction

What type of friction?

What type of friction?

What type of friction?

What type of friction?

2 Factors of Friction 1-Type of surface. 2-How hard the two surfaces push together.

Which type of hockey has more friction?

Gravity

Air Resistance and Weight Air resistance is a type of fluid friction on falling objects. Weight is the force of gravity on an object at the surface of the Earth.

Law of Universal Gravitation Gravity acts between all objects in the universe.

Gravity Between Objects The force of gravity between objects increases with greater mass and decreases with greater distance.

Gravity

Gravity is the force that pulls objects toward the Earth- acceleration due to gravity is 9.8m/s/s.

Newton’s Third law If an object exerts a force on another object, the second object, exerts an equal force in the opposite direction.

Momentum = mass x velocity The momentum of an object is the product of its mass and velocity. In other words: Momentum = mass x velocity Kg x m/s

COLLISIONS

Law of Conservation of Momentum The total momentum of the objects that interact does not change.