Force and Motion Notes

A push or pull that has a size and a direction. Force A push or pull that has a size and a direction. Makes objects speed up, slow down, or change direction. OR

The greater the force, the greater the change in motion will be.

The larger the object, the less effect the force will have on the object.

Work The use of a force to move an object. The tree doesn’t move, so the eagle must have moved. The use of a force to move an object.

Inertia Measures an object’s tendency to resist changing its motion. Inertia depends on the amount of mass an object has. More Mass = More Inertia Less Mass = Less Inertia

Unless acted upon by a force, objects in motion tend to stay in motion and objects at rest remain at rest.

Sir Isaac Newton

Motion When an object changes position in relation to a reference point over a period of time.

Balanced Forces NO MOVEMENT! Forces that cancel each other out because they are equal and acting in opposite directions. The scale doesn’t move because it is balanced. Because balanced forces cancel each other out, there is NO MOVEMENT!

Unequal forces that do not cancel each other out. Unbalanced Forces Unequal forces that do not cancel each other out. The scale moves because it is unbalanced. Because unbalanced forces do not cancel each other out, there IS MOVEMENT!

Force that resists motion between two touching surfaces. Friction Friction between your shoes and the skateboard keeps you from sliding off as you slow down. Force that resists motion between two touching surfaces.

Friction creates heat!

If there were no friction, it would be easy to pull or push large, heavy objects across the floor.

If there were no friction, you would not be able to walk If there were no friction, you would not be able to walk! Your shoes would not grip the ground and you would slide.

Without friction you would not even be able to pick anything up, because you would not be able to grip the object. It would slip out of your hands!

To get the most out of friction, we even wear special shoes like baseball cleats, soccer cleats, basketball shoes and track shoes.

Friction wears objects down Friction wears objects down. This is why the bottoms of your shoes slowly disappear and why your parents have to buy new tires for the car.

Gravity is the pull that all objects with mass exert on other matter.

rubbing hands together person coming down a slide Comparison Map friction gravity forces causes movement produces heat rubbing hands together tires on cement person coming down a slide person falling earth holding the moon apple falling