1. Is a force necessary to keep an object in motion?
Forces & Motion
Is a force necessary to keep an object in motion?

2. FORCES
Unbalanced
Balanced

3. GRAVITY: force that depends on mass and distance between 2 objects
Acceleration
Free fall
All objects accelerate to Earth at a rate of 9.8m/s/s
The distance an object falls increases each second it falls (recognize the pattern)
Happens only when there is no air resistance.
It is impossible to be “weightless” !
Astronauts “float” in orbiting space shuttles.
An orbit is the curved path when forward motion and free fall are combined.

4. Speed>>>Velocity>>>Acceleration Acceleration is a change in velocity.
Speed = distance /time
Velocity = speed with a direction 19.6m/s downward
19.6m/s
Acceleration = gravity X time 9.8m/s/s X 3seconds =
29.4m/s As he falls, each second he falls F A R T H E R !

5. Friction, force that opposes motion
Harmful
Wears tire tread
Rope burns on hands,
heats the tiles on the space shuttles
Helpful
Air resistance is fluid friction
Gives traction, like to open a jar of pickles

6. 7.6B Student will demonstrate that an object will remain at rest or move at a constant speed & in a straight line if it is not being subjected to an unbalanced force.