September 30, 201HW: PTG #1-4, Due Tuesday

Do Now: on handout WDYS WDYT▪ TB pg. 105

Agenda: Do Now Objective/Success

Criteria Investigate

Learning Objective: Describe the connection

among speed, friction, and radius of a curve when turning.

Success Criteria: Recognize the need for a

centripetal force when rounding a curve

Predict the effect of an inadequate centripetal force

Relate speed to centripetal force

Calculate maximum safe speed when driving on a curve

DO NOW

In your own words… Describe what reaction time is….How does

reaction time affect driving? Describe what benefits friction force has on

driving an automobile down a road?Why?

Important upcoming dates Quiz: Tuesday 10/4 Chapter 1 Test 10/11 Chapter Challenge Due

October 12 (Presentations) October 5 (Class work day)

September 30, 2011HW: PTG #1-4, Due Tuesday

Do Now: Read through

procedures #1, 2, 8-12 on pgs 105-109

Agenda: Do Now Objective/Success

Criteria Investigate

Learning Objective: Describe the connection among

speed, friction, and radius of a curve when turning using words and equations.

Describe the forces acting on an object traveling in a circle.

Success Criteria: Recognize the need for a

centripetal force when rounding a curve

Predict the effect of an inadequate centripetal force

Relate speed to centripetal force Calculate maximum safe speed

when driving on a curve

September 30, 2011HW: PTG #1-4, Due Tuesday

Do Now: Predict what will happen in

Investigate #9 on pg. 107.▪ As radius increases, maximum

safe speed ___________ (increases, decreases, stays the same)

▪ As the curve in the road gets tighter, you have to ________ (slow down, speed up, go the same speed)

Agenda: Do Now Objective/Success Criteria Investigate Physics Talk

Learning Objective: Describe the connection among

speed, friction, and radius of a curve when turning using words and equations.

Describe the forces acting on an object traveling in a circle.

Success Criteria: Recognize the need for a

centripetal force when rounding a curve

Predict the effect of an inadequate centripetal force

Relate speed to centripetal force Calculate maximum safe speed

when driving on a curve

Physics Talk 1.7 Notes

What is a force?

What forces were acting on the car that makes it go in a circle?

a push or a pull

Ladybug Motion

Ladybug Motion

Physics Talk 1.7 Notes

Why does the car turn?

Newton’s Law: an object in motion will stay in motion in a straight line at a constant speed unless a force acts on it.

Force toward the center of the circle keeps the object moving in a circle

Physics Talk 1.7 Notes

What is centripetal force?

The force directed toward the center to keep an object moving in a circular path. String on car Friction between

block and turntable Friction between

wheels and road

Physics Talk 1.7 Notes

What is centripetal acceleration?

Remember:Speed:

change in distance per unit time

Velocity:change in distance per unit time in a direction.

Acceleration:change in velocity per unit time

Centripetal acceleration: change in direction of velocity with respect to time

Physics Talk 1.7 Talk

How do you calculate speed of a turning object?

V=d/t Circumfrence=2∏r V=2∏r/t

SOLVE

A student is spinning a turntable with a wooden block resting on it. The block is located 40 cm from the center of the table and the turntable is rotating 20 times every minute. What is the speed of the wooden block on the turn table?

Quick Notes:

How can an object accelerate with out changing it’s speed?

Grab an accelerometer and see if you can accelerate while moving at constant speed. What did you do?

Quick Notes

14.Identify what causes the Centripetal force for the following:

a) Moon revolving around Earthb) Car turning on the roadc) Cork on a stringd) Kid on amusement park ride

Homework

PTG Pg 114#1-4

1.7 Quiz