INERTIA  An object will remain at rest or in constant motion unless acted upon by an unbalanced force. “THE OLD TABLECLOTH TRICK”

WHICH HAS MORE MASS?

LESS MASS = LESS INERTIA  The skier does not have a lot of mass therefore has LESS inertia; & is easier to stop MORE MASS = MORE INERTIA  The car has MORE MASS therefore has A LOT OF INERTIA; & is harder to stop

Finger applies a force to a card causing it to move Penny STAYS at rest (over the cup) due to inertia Gravity causes the penny to fall into cup

 What happened to the spinning hardboiled egg when you tapped it?  The egg stopped spinning  Why?  The egg is a solid unit and the finger applied enough force to change the inertia  What happened to the spinning raw egg when you tapped it & let go?  The egg continued to spin  Why?  The liquids inside the egg were in motion & wanted to stay in motion due to inertia

 Which cup was easier to keep standing?  The cup (more massive one) because it has more inertia  The empty cup was harder to keep standing because it has less mass therefore less inertia

Vectors- arrows that show the direction & strength (magnitude) of a force Longer Arrow = Stronger Force Shorter Arrow = Weaker Force Forces measured in Newtons (N)

 Cancel each other out so net force = O  Results in NO MOTION or NO CHANGE in motion

 Forces that don’t cancel & the object moves in the direction of the stronger force.  DIFFERENT directions, SUBTRACT the forces  SAME direction, ADD the forces.

 An object acted on by an unbalanced force accelerated in the direction of the force

 Force= mass x acceleration  Mass (kg or grams)  Acceleration (m/s 2 )  1 Newton= force needed to move 1 kg 1 m/s 2

 More Mass = More Gravity  Earth has more gravity than Moon b/c Earth is more massive  More Distance = Less gravity  Acceleration due to Gravity = 9.8 m/s 2