# Unit 4 Midterm Review

### Bradley Sposit

## Key Concepts of Unit 4

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

## 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

__Tangent-__ Opposite divided by adjacent

__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

## Practice Questions

## Question #1 You walk 30m south and 30m east. Find the magnitude and direction of the resultant displacement both graphically and algebraically. | ## Question #2 A ship leaves its home port expecting to travel to a port 500 km due south. Before it moves even 1 km, a severe storm blows it 100km due east. How far is the ship from its destination? In what direction must it travel to reach its destination? | ## Question #3 A river flows toward the east. Because of your knowledge of physics, you head your boat 53 degrees west of north and have a velocity of 6 m/s due north relative to the shore. a) What is the velocity of the current? b) What is your speed relative to the water? |