Forces in Motion

What Do You Think?

Explain what you know about Newton’s Laws of

Motion.

Forces in Motion

Newton’s Laws of Motion

http://academic.brooklyn.cuny.edu/history/virtual/portrait.htm

In 1686, Sir Isaac Newton explained the relationship between force and motion with his three laws of motion.

Forces in Motion

Newton’s First Law of Motion

1. An object at rest remains at rest until its acted on by an unbalanced force.

2. An object stays in motion at the same speed and in the same direction until its acted on by an unbalanced force.

Forces in Motion

http://www.physicsclassroom.com/mmedia/newtlaws/efarm.htl

How does this illustrate Newton’s First Law?

Forces in Motion

Newton’s First Law is also called the Law of Inertia.

Inertia is the tendency of all objects to resist any change in motion.

Forces in Motion

Newton’s First Law is also called the Law of Inertia.

Example…your mom makes a sharp left turn in the car…you slide toward the door.

Forces in Motion

Newton’s Second Law of Motion

When applying the same force on an object, as an acceleration increases, its mass decreases.

Forces in Motion

Newton’s Second Law of Motion

If you are applying the same force on an object, an objects acceleration decreases as its mass increases.

Forces in Motion

Newton’s Second Law continued…

• An object’s acceleration increases as the force on the object increases

• An object’s acceleration decreases as the force on an object decreases.

Forces in Motion

Activity

Tell your neighbor 2 ways a grocery store shopping cart could illustrate Newton’s Second Law?

Forces in Motion

Newton’s Third Law of Motion

• All forces act in pairs.

• If a force is exerted, another force is exerted that is equal in size, but opposite in direction to the first force.

Forces in MotionClick below to see examples of

Newton’s Third Law

http://www5.unitedstreaming.com/index.cfm

Forces in MotionNewton’s Third Law also deals with

momentum• Momentum is a property of a moving

object.• Momentum depends on the objects

mass and velocity.• If a small car and a large truck are both

traveling down the highway at the same velocity, the truck has more mass, therefore it will have more momentum.

Forces in Motion

Momentum is Conserved

When a moving object hits another object, the momentum of the first object transfers to the second object.

Forces in Motion

Momentum is Conserved

• Example:–When one pool ball hits another

pool ball on a pool table, the momentum of the first ball is transferred to the second ball as it hits.

Forces in Motion

The momentum of this truck is transferred to this car.

http://www.physicsclassroom.com/mmedia/momentum/trece.html