# Gravity and Rotational Motion

Pages: 21 (3006 words) Published: December 4, 2012
KEY
KEY
These Physics NOTES belong to

Name ____________________________________ Date __________ Period _____

Unit 5: Circular Motion and the Law of Gravity Ch. 7&8
Skills to Review or Learn:
Memorize/use/convert SI units
Apply Newton’s laws
to circular motion

Skills to Review or Learn:
Memorize/use/convert SI units
Apply Newton’s laws
to circular motion

I am responsible forVocabulary to know
Centripetal
Tangential
Gravitational
Torque

I am responsible forVocabulary to know
Centripetal
Tangential
Gravitational
Torque

7.1 ROTATIONAL MOTION

A car is driving at a constant speed of 13.6 m/s (about 30 mph), moving counter-clockwise on a circular track as shown.
yes
yes

a) Is this car accelerating? ____________
b) If the car suddenly lost all traction and started
skidding exactly when it is at the location, sketch
which direction will it skid (if the driver does nothing).

Change in velocity as time goes by
Change in velocity as time goes by
Review Acceleration:
Magnitude or direction (not units)
Direction only

Magnitude or direction (not units)
Direction only

Acceleration means _______________________________________________
What CAN change for a velocity vector? _____________________________________ What IS changing when something moves in a circle? ____________________________

an object in motion continues in constant-velocity motion in a straight line an object in motion continues in constant-velocity motion in a straight line Review Newton’s 1st Law:
An object at rest remains at rest, OR ____________________________________________ _________________________________________________________________________ UNLESS the object experiences a net or unbalanced external force.

Example 1: The car accelerates at locations A and at B. Describe the direction your body seems to move for just the first few seconds of the car’s acceleration: toward the front, back, left or right side of car. At location A, the car accelerates by GOING SLOWER.

In the car, your body seems to move toward ________________ Why? _______________________________________________
Is there a force pushing you in this direction? _______________

At location B, the car accelerates by TURNING RIGHT.
In the car, your body seems to move toward ________________ Why? ________________________________________________
Is there a force pushing you in this direction? ________________

At location A, the car accelerates by GOING SLOWER.
In the car, your body seems to move toward ________________ Why? _______________________________________________
Is there a force pushing you in this direction? _______________

At location B, the car accelerates by TURNING RIGHT.
In the car, your body seems to move toward ________________ Why? ________________________________________________
Is there a force pushing you in this direction? ________________

the front (West)
Your body wants to keep the OLD VELOCITY’s speed (FAST) NO. This is INERTIA
the front (West)
Your body wants to keep the OLD VELOCITY’s speed (FAST) NO. This is INERTIA

A
B
A
B

the left (West!)
Your body wants to keep OLD VELCOCITY’s direction (WEST) NO. This is INERTIA
the left (West!)
Your body wants to keep OLD VELCOCITY’s direction (WEST) NO. This is INERTIA
N
W E
S
N
W E
S

Eventually, the car “wins” – the car does exert forces on you, and you do accelerate with it. But...