Forces and Motion

Motion change of position

Speed change of position over time Speed = distance ÷ time

Velocity Speed AND direction of an object Velocity is always written as speed and direction. For example: 25mph, north or 55km per hour, west.

Acceleration Any change in speed or direction It takes more force to accelerate an object with a lot of mass than a smaller object.

Force any push or pull Force causes acceleration, more force causes MORE acceleration and less force causes LESS acceleration.

Inertia the property of matter that keeps objects moving or keeps them at rest.

Gravity: force of attraction between Earth and other objects. Gravitation: force of attraction between ANY two objects

Weight: measure of gravitational force on an object

Friction force that resists motion between objects that are touching. Friction causes objects to slow down and stop

What’s my speed? Speed = distance ÷ time Ms. Calkins drove 120 miles to Atlanta. She got there in two hours. What was her speed? A racehorse ran 3 miles in 3 minutes. What was its speed? A rocket traveled 25 miles in 5 minutes. What was its speed?

Think it through! Sally wants to move a heavy box. Explain why she would need to apply more FORCE to slide the box on a carpeted floor than a wood floor. Why does a basketball left on the court stay in one place? What is needed before it moves? What determines how fast it moves and in what direction it moves?

Sally has to overcome the FRICTION caused by the surface of the box touching the surface of the floor. She has to apply more FORCE when pushing across carpet.

Because of INERTIA, a ball will sit still until a FORCE is applied to it. If you push or kick the ball it will roll in the same direction that the force is applied. In other words, it goes the way you push it.

That’s how to move it move it…