Physics 141H
Homework Set #3
Chapter 3:
Multiple-choice:
1) Newtons First Law tells us that if no force acts on an object, its velocity will never
change. (D)
3) With the band stretched to the 7in mark , the block has not yet started to move. This
means i
Physics 141H
Solutions for Homework Set #2
Chapter 2:
Multiple-choice:
2) An object is moving towards O would have a displacement vector whose magnitude
decreases with time, or:
dr
<0
dt
|r| is given by
x 2 + y 2 , so using the chain rule for derivatives
Physics 141H
Solutions to Homework Set #1
Chapter 1:
Multiple-choice:
1) Since each measurement has three significant figures, the result should also have three
significant figures. (D)
3) We want to find the period of the oscillator. Period has dimension
Physics 141H
Solutions to Homework Set #12
Chapter 10:
Multiple choice:
3)
a) Using the definition of angular momentum for a particle, we find:
L = rp
dL dr
dp
=
p+r
= vp +0
dt
dt
dt
Since v is parallel to p, v p = 0 , and therefore the angular momentum i
Physics 141H
Solutions for Homework Set #11
Chapter 9:
Multiple choice:
7) The forces on the ladder are as follows:
N1
f1
mmg
h
mlg
N2
f2
x
d
The condition for the ladder to avoid slipping is to have the net force and net torque both
zero. The torque abou
Physics 141H
Solutions for Homework Set #10
Chapter 13:
Multiple choice:
11) We can completely specify the motion of particles C and D if we know every
component of the velocity vector for each particle. This means there are six unknown
quantities. We do,
Physics 141H
Solutions for Homework Set #9
Chapter 12:
Multiple choice:
10)
a) When the speed is zero, the kinetic energy of the particle is zero. Since in general the
total energy E is the sum of the kinetic and potential energies, the kinetic energy is
Physics 141H
Solutions for Homework Set #8
Chapter 11:
Questions:
28) Since this is an elastic collision, we have:
pi = m Av A,i = p f = m Av A, f + mB vB , f
1
1
1
2
2
2
KE i = m Av A,i = KE f = mAv A, f + mB vB , f
2
2
2
Using these equations, we can de
Physics 141H
Solutions for Homework Set #7
Chapter 7:
Questions:
17) Yes they do. To see why, consider the case (Case 1) where they all jump at once.
Just before they leap off the car, theyve already given it its final velocity. The final state
then consi
Physics 141H
Solutions for Homework Set #6
Chapter 6:
22) Lets consider the frame where the Earth is at rest before the collision. The initial
momentum of the Earth + meteorite system is:
pi = mm vm + mE ( 0 ) = mm vm
After the collision, the Earth + mete
Physics 141H
Solutions for Homework Set #5
Chapter 5:
Multiple choice:
8)
(a) The maximum force exerted by static friction is S N . Since the block is resting on a
level surface, N = mg . So the maximum frictional force is
f = S mg = ( 0.80 ) ( 2.0kg ) (
Physics 141H
Homework Set #4 Solutions
Chapter 4:
Multiple-choice:
4) The maximum net force will result when the two forces are in the same direction. If
so, the net force will have magnitude F1 + F2. The minimum net force will occur if the
two forces are