Helpful Hints for the Exam Tomorrow

Forces:

• If there is a net force, that means an object is ACCELERATING.
• If there is NO net force (equilibrium), the object can still be moving, but there can't be a change in speed
• If something is moving at CONSTANT speed, then the sum of all the forces must be 0
• If something is moving at CONSTANT acceleration, then the NET FORCE must be constant.
• On an inclined plane, the parellel force is the weight * sin of angle.
• On an inclined plane, the perpendicular force is the weight * cos of angle
• When in doubt, use the equation Fnet = m * a
• As you make the angle of an incline greater, the parallel force increases (the object is more likely to slide down), and the perpendicular force decreases (the normal force decreases, also causing the object to slide).
• The direction of friction is always opposite the direction of motion.

Gravitational Force: F = (Gm1m2/r^2)

• If I double the mass of one object, I double the gravitational force between the two objects
• If I triple the distance between two objects, the force becomes 1/3^2 = 1/9 as big
• If I double mass, and distance, the force will still decrease because distance factors more than one mass

You should be comfortable drawing free body diagrams, identifying tension in a pulley system, and using the big 5 motion equations for horizontal and vertical motion.