# Physics 1303,1403 - Spring 1998

# Homework Assignment #5

**Due:** 26 March

### READING

Chapters 9 and 10.
### QUESTIONS

Chapter 9 - 1, 3, 4, 6, 12, 13, 17, 7, 19, 23, 24, 26, 28.

Chapter 10 - 1, 2, 4, 8, 14, 15, 16, 17.
### PROBLEMS

Chapter 9 - 2, 3, 4, 5, 15A, 15, 18, 25, 41, 47, 57, 58, 59 (try 62).

Chapter 10 - 1, 6, 13, 17, 23, 25, 32A, 32, 33, 34, 35, 43.
### ANSWERS

These are the ANSWERS only, not the SOLUTIONS. It is not sufficient to
copy these and turn them in as homework. You must show your work.
**Q 9-1)** If K=0, then p=0. If E=0, then the linear momentum can be
anything at all.

**Q 9-3)** Their momenta have equal magnitudes, but the directions can vary.

**Q 9-4)** No.

**Q 9-6)** No. Yes.

**Q 9-12)** Yes, e.g. a doughnut.

**Q 9-13)** 9.8 m/s^{2}

**Q 9-17)** The gun recoiled.

**Q 9-7)** The Earth moves, but imperceptibly because of its large mass.

**Q 9-19)** The Earth moves, but imperceptibly because of its large mass.

**Q 9-23)** System = ball + Earth

**Q 9-24)** a) Yes. b) No.

**Q 9-26)** Largest in c

**Q 9-28)** The force is small because the impulse is spread over a long
time.

**Q 10-1)** 0.105 rad/s into the clock face, zero angular acceleration

**Q 10-2)** Along the positive z-axis. Along the negative z-axis.

**Q 10-4)** 4.71 rad/s, 0 rad/s^{2}

**Q 10-8)** Measure the mass of the block [m], the linear acceleration of
the block [a], and the radius of the wheel [R]. Then solve
equation (5) in example 10.12 for the moment of inertia of
the wheel [I].

**Q 10-14)** No.

**Q 10-15)** No.

**Q 10-16)** Yes.

**Q 10-17)** The moment of inertia of the Earth about an axis through the
poles would decrease.

**P 9-2)** 8570 m/s

**P 9-3)** 1600 N up

**P 9-4)** 0.732 kg.m/s

**P 9-5)**
- 12.0 N s
- 6.00 m/s
- 4.00 m/s
- 2.40 N

**P 9-15A)** (-2 m v sin 60 / t, 0 )

**P 9-15)** (-260, 0) N

**P 9-18)** -6.00 m/s (to the left)

**P 9-25)** 301 m/s

**P 9-41)** (3.00, -1.20) m/s

**P 9-47)** 2.50 m/s at -60 degrees = (1.25, -2.16) m/s

**P 9-57)** (11.7, 13.3) cm

**P 9-58)** 1.20 m

**P 9-59)**
- (1.40, 2.40) m/s
- (7.00, 12.0) kg.m/s

**P 9-62)** 0.700 m

**P 10-1)**
- 4.00 rad/s
^{2}
- 18.0 rad

**P 10-6)**
- theta(0) = 5.00 rad; theta(3 s) = 53.0 rad
- omega(0) = 10.0 rad/s; omega(3 s) = 22.0 rad/s
- alpha(0) = 4.00 rad/s
^{2} = alpha(3 s)

**P 10-13)**
- 126 rad/s
- 3.78 m/s
- 1270 m/s
^{2}
- 20.2 m

**P 10-17)**
- 143 kg.m
^{2}
- 2570 J

**P 10-23)**
- 3/2 MR
^{2}
- 7/5 MR
^{2}

**P 10-25)** -3.55 N.m

**P 10-32A)**

**P 10-32)** 2.36 m/s

**P 10-33)**
- 2 Sqrt(Rg/3)
- 4 Sqrt(Rg/3)
- Sqrt(Rg)

**P 10-34)** 0.31

**P 10-35)**
- T = 11.4 N; a = 7.57 m/s
^{2}; v = 9.53 m/s
- v = 9.53 m/s

**P 10-43)**
- Sqrt(3g/L)
- 3g/(2L)
- (-3g/2, 3g/4)
- (-3mg/2, mg/4)

Please report any corrections to
Professor Scalise.

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