# Homework Assignment #5

Due: 26 March

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.

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/s2
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 10-8) 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)
1. 12.0 N s
2. 6.00 m/s
3. 4.00 m/s
4. 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. (1.40, 2.40) m/s
2. (7.00, 12.0) kg.m/s

P 9-62) 0.700 m
P 10-1)

P 10-6)
3. alpha(0) = 4.00 rad/s2 = alpha(3 s)

P 10-13)
2. 3.78 m/s
3. 1270 m/s2
4. 20.2 m

P 10-17)
1. 143 kg.m2
2. 2570 J

P 10-23)
1. 3/2 MR2
2. 7/5 MR2

P 10-25) -3.55 N.m
P 10-32A)
P 10-32) 2.36 m/s
P 10-33)
1. 2 Sqrt(Rg/3)
2. 4 Sqrt(Rg/3)
3. Sqrt(Rg)

P 10-34) 0.31
P 10-35)
1. T = 11.4 N; a = 7.57 m/s2; v = 9.53 m/s
2. v = 9.53 m/s

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

Please report any corrections to Professor Scalise.