# November 2 AP Physics.

## Presentation on theme: "November 2 AP Physics."— Presentation transcript:

November 2 AP Physics

Momentum Test return

In: What makes objects move in a circle?

Objective: To begin our study of circular motion. Success criteria:
Discover the variables of centripetal force, and be able to do centripetal force and acceleration problems.

Discovery Lab: Circular motion
Using the circular motion device, discover everything you can about circular motion. List your discoveries:

What did we find out?

Period (T) is the time it takes to go around once.
Frequency ( f ) the number of times it goes around in one second T=1/ f

Centripetal acceleration
Always toward the center ac= v2 r

“Center seeking” force
Centripetal force: “Center seeking” force Fc= mv2 r

V=d/t Distance = 2πr Time=T (period) So……. V= 2πr T
Tangential Speed V=d/t Distance = 2πr Time=T (period) So……. V= 2πr T

Problem A 2.1 m rope attaches a tire to an overhanging tree limb. A girl swinging on the tire has a tangential speed of 2.5 m/s. If the magnitude of the centripetal force is 88 N, what is the girl’s mass?

A bicyclist is riding at a tangential speed of 13
A bicyclist is riding at a tangential speed of 13.2 m/s around a circular track. The magnitude of the centripetal force is 377N, and the combined mass of the bicycle and rider is 86.5 kg. What is the track’s radius?

A dog sits 1.5 m from the center of a merry-go round and revolves at a tangential speed of 1.8 m/s. If the dog’s mas is 18.5 kg, what is the magnitude of the centripetal force on the dog?

A 905 kg car travels around a circular track with a circumference of 3
A 905 kg car travels around a circular track with a circumference of 3.25 km. If the magnitude of the centripetal force is 2140 N, what is the car’s tangential speed?

Practice Problems:

What makes objects move in a circle?
Out: What makes objects move in a circle?