# Unit 4 Midterm Review

## Key Concepts of Unit 4

1. Force body diagrams- You need to know how to explain and draw them.
2. Describe the relationship between net force, mass, and acceleration.
3. Calculate the net force, mass, or acceleration of an object.
4. Explain the difference between mass and weight given a changing gravitational field.
5. Evaluate and develop a mathematical model for elastic (spring) forces.
6. Predict the force required to slide an object relating to the coefficient of friction.
7. NEWTONS SECOND LAW!!!!!

## Formulas

• Fnet = m*a
• a = Δv / Δt
• Δx= ½ at^2 (if v0 = 0)
• Fc = mv^2 / r
• ac = v^2 / r
• Felastic = k Δx
• v1^2 = v0^2 + 2a (Δx)
• Fk = μk*FN

## Vocabulary

Circular- A circle shape

Centripetal- Think of the "bucket and rope" trick

Centrifugal- is the effect that tends to move an object away from the center of a circle it is rotating about

Free-body diagram- The arrow diagram that shows forces on a object

Friction- The force resisting the relative motion of solid surfaces

Kinetic- Resistance to objects in motion

Static- Stationary friction

Linear- A direct relationship (straight line)

Normal force- The force that is perpendicular to the surface

Net force- The overall force acting on an object

Torque- A measure of force acting on an object that causes it to rotate

Weight- Mass*Gravity

Apparent Weight- force exerted on a scale

Weightlessness- Apparent weight is zero