Uniform Circular Motion

1
Uniform Circular Motion
2
CPS Question

• What is the direction of acceleration of an
  object in uniform circular motion?

• Away from the axis.
• Toward the axis.
• Tangent to the path.
• Acceleration is zero.

3
CPS Question

• Two balls with the same speed contact different
  semicircular guides. Which has the greatest
  centripetal acceleration?

A. Ball A. B. Ball B. C. Its a tie. D. Need more
information.
4
CPS Question

• A and B stand the on edge of identical carousels.
  B has a greater tangential speed. Which has the
  greater centripetal acceleration?

A. A. B. B. C. Its a tie. D. Need more
information.
A
B
5
CPS Question

• Points A and B are different distances from the
  center of a rotating disk. Which has the greater
  centripetal acceleration?

A. A. B. B. C. Its a tie. D. Need more
information.
6
CPS Question
When does a vector cross product have the
greatest magnitude?

• When q 90.
• When q 0 or 180.
• Both of these.
• Neither of these.

7
CPS Question
The vector cross product is commutative.

• True.
• False.

8
CPS Question

• The two hoops have the same mass and roll with
  identical speeds. Which has the greater angular
  momentum?

• Hoop A.
• Hoop B.
• Both hoops have the same angular momentum.

9
CPS Question

• The two hoops have the same mass and skid with
  identical speeds, giving them identical forces of
  friction. Which experiences the greater torque?

• Hoop A.
• Hoop B.
• Both hoops experience the same torque.

10
Heat
11
CPS Question

• Which has the greatest specific heat?

• 1 kg water.
• 1000 kg water.
• Both have the same specific heat.

12
CPS Question

• Which has the greatest heat capacity?

• 1 kg water.
• 1000 kg water.
• Both have the same heat capacity.

13
CPS Question

• Water has a specific heat of about 4,000 J/(kg?C
  ). Ice has a heat of fusion of about 300,000
  J/kg. If 0.1 kg 0?C ice is added to 1 kg 50?C
  water, can the ice cool the water to 0?C?

• Yes.
• No.

To cool the water4000 J/(kg?C)50?C1 kg
200,000 J To melt the ice300,000 J/kg0.1
kg 30,000 J
14
Entropy

• never decreases overall

15
CPS Question

• When a ball bounces until it comes to a stop,
  what changes take place?

• The balls potential energy decreases.
• The entropy of the universe increases.
• The balls temperature increases.
• All of these.

16
CPS Question

• When a ball bounces until it comes to a stop,
  what quantity becomes more dispersed?

• Energy becomes more dispersed.
• Matter becomes more dispersed.
• Both become more dispersed.
• Neither becomes more dispersed.

17
CPS Question

• A handful of marbles spills onto the floor.
  Different marbles roll to different ends of the
  room. Which quantity becomes more dispersed in
  that process?

• Energy becomes more dispersed.
• Matter becomes more dispersed.
• Both become more dispersed.
• Neither becomes more dispersed.

18
CPS Question

• Liquid water placed in a vacuum boils until it
  freezes. Which quantity becomes more dispersed
  in that process?

• Energy becomes more dispersed.
• Matter becomes more dispersed.
• Both become more dispersed.
• Neither becomes more dispersed.

19
Springs

• force and motion

20
CPS Question

• Identical weights are hung from different
  springs. Spring A stretches farther than spring
  B. Which spring has the larger spring constant
  k?

• Spring A.
• Spring B.
• The two ks are the same.
• Cant tell.

21
CPS Question

• Identical weights are hung from different
  springs. Spring A stretches farther than spring
  B. Which weight did the most spring-stretching
  work?

• The weight on spring A.
• The weight on spring B.
• Both weights did the same work.
• Cant tell.

22
CPS Question
At which event is the force the greatest?
A. B. C.
23
CPS Question
At which event is the speed the greatest?
A. B. C.
24
CPS Question
At which event is the acceleration the greatest?
A. B. C.
25
CPS Question
At which event is the potential energy the
greatest?
A. B. C.
26
CPS Question
At which event is the kinetic energy the greatest?
A. B. C.
27
CPS Question

• Two blocks oscillate on identical springs. The
  mass of block A is twice the mass of block B.
  How does As oscillation period compare to Bs?

28
Waves
29
CPS Question

• For a given speed of wave, how are frequency and
  wavelength related?

• Higher frequency means longer wavelength.
• Higher frequency means shorter wavelength.

30
CPS Question

• Where do ocean waves approaching the shore move
  fastest?

• Far from the shore.
• Near the shore.
• Same speed everywhere.

31
CPS Question

• Where are ocean waves approaching the shore
  highest?

• Far from the shore.
• Near the shore.
• Same amplitude everywhere.

32
Wave Refraction
Speed u1
q1
Snells Law u2 sinq1 u1 sinq2
Speed u2
q2
33
Ocean Wave Refraction
34
CPS Question

• When do waves interfere constructively?

• When the trough of one wave meets the crest of
  the other wave.
• Only when the crest of one wave meets the crest
  of another wave.
• When the two waves are in the same phase.

35
CPS Question

• When do waves combine to form beats?

• When a wave meets its reflection.
• When a fundamental meets an overtone.
• When a wave meets another with a similar
  frequency.
• When a wave resonates inside a cavity of the
  proper size.

36
CPS Question

• When waves of frequency f1 and f2 combine, what
  is the resulting beat frequency?

• f1 f2.
• (f1 f2)/2.
• f1f2.
• f1f2.