# Unit 4 - Force & Acceleration

## Vocabulary

circular- Motion of an object in a circle in a constant speed

centripetal- Makes a body follow a curved path

centrifugal- A force that causes an object moving in a circular path to move out & away from the center of its path

free-body diagram- Used to show direction & magnitude of all forces

friction- Resisting force to the relative motion of solid surfaces

kinetic- Resulting from motion

static- Not moving

linear- Resembling a line

normal force- Perpendicular to the surface, opposite of gravity

net force- Overall force on an object

tangent- Line to a plane curve at a given point is the straight line that just touches the curve

torque- Tendency of a force to rotate around the axis

weight- Body's relative mass

apparent- The upward force, opposes gravity & prevents a supported object from falling

weightlessness- The bodies are approximately weightless

## Formulas

Fnet = m a

a = Δv / Δt

Δx= ½ at2 (if v0 = 0)

v12 = v02 + 2a (Δx)

Felastic = k Δx

Fk = μkFN

ac = v2 / r

Fc = mv2 / r

## Learning Targets

1. Q- What would a force body diagram look like for a book sitting on a table?

2. Q- What would be a good example of a FBD of a two dimension force?

3. Q- What are the formulas for net force, mass, and acceleration and how do they relate to each other?

4. Q- What are the equations for net force, mass, and acceleration?

5. Q- What is the definition of mass and weight and how do they differ from each other?

6. Q- What is apparent weight & would an elevator be a good example of apparent weight?

7. Q- What would be a good example of a model for a spring force?

8. Q- What would be the force required to slide a box across the ground due to friction?

9. Q- What would the speed be on the rotor if the radius was 3.0 m and the ride takes 2 seconds?

## Big Ideas Of Unit 4

Newtons 2nd Law- The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.