Phys1220 Fall-2014 Exam-1
1. The symbols for area, volume flow rate, and speed are, respectively, A, R, and v.
The SI units of area, volume flow rate, and speed are, respectively, square meters,
cubic meters per second, and meters per second. Which is the
Phys1220 Exam-2 Spring2015
1. The x and y coordinates of a 2.0-kg particle moving in the xy plane under the
influence of a net force F are given by x = 1.5 t2 and y = (1/3) t3 - 3 t2, with x and y in
meters and t in seconds. What is the magnitude of the f
37.1. Model: S and S are inertial frames that overlap at t = 0. Frame S moves with a speed v = 5.0 m/s
along x-direction relative to frame S. Visualize: the
The figure shows a pictorial representation of the S and S frames at t = 1.0 s and 5.0 s. Solve: F
36.1. Model: A phasor is a vector that rotates counterclockwise around the origin at angular frequency .
Solve: (a) Referring to the phasor in Figure EX36.1, the phase angle is
t = 180 + 30 = 210
(b) The instantaneous value of the emf is
35.1. Model: Apply the Galilean transformation of velocity.
Solve: (a) In the laboratory frame S, the speed of the proton is
m/s ) + (1.41 106 m/s ) = 2.0 106 m/s
The angle the velocity vector makes with the positive y-axis is
= tan 1
To develop a motional emf the magnetic field needs to be perpendicular to both, so lets say its direction is into the page. Solve: This is a straightforward use of Equation 34.3. We have
E 1.0 V = = 2.0 104 m/s lB (1.0 m ) ( 5.
33.1. Model: A magnetic field is caused by an electric current.
Visualize: Please refer to Figure EX33.1.
Solve: The magnitude of the magnetic field at point 1 is 2.0 mT and its direction can be determined by using
the right-hand rule. Grab the current ca
From the circuit in Figure EX32.1, we see that 50 and 100 resistors are connected in series across the battery. Another resistor of 75 is also connected across the battery.
32.2. Solve: In Figure EX32.2, the positive terminal of the battery i
31.1. Solve: The wires cross-sectional area is A = r 2 = (1.0 103 m ) = 3.1415 106 m 2 , and the electron
current through this wire is i = 31.3, the drift velocity is
Ne = 2.0 1019 s 1 . Using Table 31.1 for the electron density of iron and Equatio
30.1. Solve: The potential difference V between two points in space is
V = V ( xf ) V ( xi ) = Ex dx
where x is the position along a line from point i to point f. When the electric field is uniform,
V = Ex dx = Ex x = (1000 V/m )( 0.30 m 0.10 m ) =
29.1. Model: The mechanical energy of the proton is conserved. A parallel-plate capacitor has a uniform
electric field. Visualize:
The figure shows the before-and-after pictorial representation. The proton has an initial speed vi = 0 m/s and a final speed
As discussed in Section 28.1, the symmetry of the electric field must match the symmetry of the charge distribution. In particular, the electric field of a cylindrically symmetric charge distribution cannot have a component parallel to th
Model: The electric field is that of the two charges placed on the y-axis.
Visualize: Please refer to Figure EX27.1. We denote the upper charge by q1 and the lower charge by q2.
Because both the charges are positive, their electric fields at P are d
26.1. Model: Use the charge model.
Solve: (a) In the process of charging by rubbing, electrons are removed from one material and transferred to the other because they are relatively free to move. Protons, on the other hand, are tightly bound in nuclei. So
25.1. Model: Balmers formula predicts a series of spectral lines in the hydrogen spectrum.
Solve: Substituting into the formula for the Balmer series,
91.18 nm 91.18 nm = = 410.3 nm 11 1 1 2 2 2 22 6 2 n
where n = 3, 4, 5, 6, and where we have used n =
38.1. Model: Current is defined as the rate at which charge flows across an area of cross section.
Solve: Since the current is Q / t and Q = N / e , the number of electrons per second is
N 10 nA 1.0 108 C/s = = = 6.25 1010 s 1 6.3 1010 s 1 t e 1.60 1019 C
39.1. Solve: A steady photoelectric current of 10 A is indicated in the graph. The number of electrons per
10 A = 10
= 1.0 10 5
C 1 electron = 6.25 1013 electrons/s s 1.6 10 19 C
39.2. Model: Light of frequency f consists of discrete quanta,
40.1. Model: The sum of the probabilities of all possible outcomes must equal 1 (100%).
Solve: The sum of the probabilities is PA + PB + PC + PD = 1. Hence, 0.40 + 0.30 + PC + PD = 1 PC + PD = 0.30 Because PC = 2PD, 2PD + PD = 0.30. This means PD = 0.10 a
Phys1220 Spring-2015 Final Exam
1. An automobile moving along a straight track changes its velocity from 40 m/s to
80 m/s in a distance of 200 m. What is the time interval of this constant
a. 12 s
b. 24 s
Solution: xi = 0
c. 20/6 s
vxi = 40
Phys1220 Exam-3 Spring2015
1. A sled after a final push moves at velocity of 5.0i m/s. However, after 8.0 s later the
sled comes to rest. If the mass of the sled is 40 kg, determine the magnitude of the
average friction force acting on the sled during thi
Phys1220 Exam-1 Spring 2014
1. Arthur and Betty start walking toward each other when they are 100 m apart.
Arthur has a speed of 3.0 m/s and Betty has a speed of 2.0 m/s. How long does it
take for them to meet?
a. 33 s.
Solution: xAi = 0
xAf = xBf
b. 50 s
Phys1220 Fall-2013 Exam-1
1. A person walks first at a constant speed of 3.0 m/s along a straight line from
point A to point B and then back along the line from B to A at a constant speed of
5.0 m/s. If the whole trips take 40 minutes, how long does it ta
Phys1220 Exam-3 Fall2014
1. A 20-g bullet moving at 1000 m/s is fired through a one-kg block of wood
emerging at a speed of 200 m/s. If the block had been originally at rest and is free to
move, what is its resulting speed?
a. 24 m/s
b. 160 m/s
c. 20 m/s
Phys1220 Exam-3 Fall 2013
1. A spring with spring constant k is used to launch a mass m up a frictionless inclined plane
having angle of elevation . What is the maximum vertical height reached above the starting
elevation of the mass during the motion of
Phys1220 Exam-3 Spring2014
1. A baseball player (m = 60 kg) is initially at rest on an extremely slippery, icy
surface. He then throws a baseball (m = 0.20 kg) with a horizontal velocity of 75 m/s.
What is the recoil velocity of the pitcher? (Assume that
Phys1220 Exam-2 Fall2014
1. A 40.0-kg block is initially at rest on a horizontal surface. A horizontal force of
280 N is required to set the block in motion, after which a horizontal force of 120 N is
required to keep the block moving with constant speed.
Phys1220 Exam-2 Fall-2013
1. A television set rests on top of a table. An upward normal force of magnitude 400
N is exerted on the television set by the table and a downward gravity force of the
same magnitude also acts on the television set. Do this upwa
Phys1220 Spring-2015 Exam-1
1. Which quantity can be converted from the English system to the metric
system by the conversion factor
a. feet per second
b. feet per hour
d. miles per minute
e. miles per hour
Solution: miles per hour
c. miles per second
43.1. Model: The nucleus is composed of Z protons and neutrons. Solve: (a) 3H has Z = 1 proton and 3 1 = 2 neutrons. (b) 40Ar has Z = 18 protons and 40 18 = 22 neutrons. (c) 40Ca has Z = 20 protons and 40 20 = 20 neutrons. (d) 239Pu has Z = 94 protons and
Solve: (a) A 4p state corresponds to n = 4 and l = 1. From Equation 42.3, the orbital angular
momentum is L = 1(1 + 1) = 2 . (b) In the case of a 5f state, n = 5 and l = 3. So, L = 3 ( 3 + 1) = 12 .
42.2. Solve: (a) Excluding spin, a state is descri