1. Gravitational Forces
Physical Science

2. Vocabulary
Define: force air resistance newton gravity net force terminal velocity friction projectile motion static friction inertia rolling friction momentum fluid friction

3. What is a force?
Any push or pull that acts on an object Measuring force – spring scales Units of force – newton (N) Representing force – (→)

4. Combining Force
Net force is the overall force acting on an object after all the forces are combined. Balanced forces – net force is zero- no change in motion Unbalanced forces – when the net force is not zero – there is acceleration

5. Gravity
A force that acts between any two masses. Falling objects: Gravity causes objects to accelerate downward. Air resistance reduces acceleration. Terminal velocity is the constant velocity when air resistance = gravity

6. Weight and Mass
Mass is a measure of the inertia of an object. Weight is a measure of the force of gravity acting on an object. W = mass X acceleration due to gravity W = mg

7. Projectile Motion
The motion of a falling object after it is given an initial forward velocity. The “curve” results from forward velocity and downward gravity.

8. Friction
Any force that opposes the motion of objects. Static friction – acts on objects that are not moving. Sliding friction – opposes the direction of motion of an object sliding. Rolling friction – the friction force that acts on rolling objects Fluid friction – opposes the motion of an object through a fluid.