Chapter 1: Representing Motion Example Questions & Problems

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Chapter 1: Representing Motion

Example Questions & Problems

Example 1.1

For each motion diagram, write a short description of the motion of an object that will match the diagram. Your descriptions should name specific objects.

Example 1.2

Draw a motion diagram for each motion described below. Use (i) the particle model and (ii) show and label the velocity vectors. a. A rocket-powered car on a test track accelerates from rest to a high speed, then coasts at constant speed after running out of fuel. Draw a dotted line across your diagram to indicate the point at which the car runs out of fuel. b. A bowling ball being returned from the pin area to the bowler starts out rolling at a constant speed. It then goes up a ramp and exits onto a level section at very low speed. You'll need

10 or 12 points to indicate the motion clearly.

c. A car is parked on a hill. The brakes fail, and the car rolls down the hill with an everyincreasing speed. At the bottom of the hill it runs into a thick hedge and gently comes to a halt. d. Andy is standing on the street. Bob is standing on the second-floor balcony of their apartment, about 30 feet back from the street. Andy throws a baseball to Bob. Consider the ball's motion from the moment it leaves Andy's hand until a microsecond before Bob catches it.

Example 1.3

The end of Hubbard Glacier in Alaska advances by an average of 105 feet per year. What isthe speed of advance of the glacier in m/s?

Example 1.4

Blades of grass grow from the bottom, so, as growth occurs, the top of the blade moves upward.

During the summer, when your lawn is growing quickly, estimate this speed in m/s. Explain how you made this estimate, and express your result in scientific notation.

Example 1.5

Shannon decides to check the accuracy of her speedometer. She adjusts her speed to read exactly 70 mph on her speedometer and holds this steady, measuring the time between successive mile markers separated by exactly 1.00 mile. If she measures a time of 54 s, is her speedometer accurate? If not, is the speed it shows too high or too low?

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