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Phys 12
Exam Review
Momentum Problems
1.Sphere A of mass 2.0 kg is travelling at 10.0 m/s[W] and approaches sphere B
of mass 5.0 kg travelling at 5.0 m/s[N]. They have a collision. Sphere A moves away at 4.0 m/s[E35°
N] and sphere B moves off in a northwesterly direction.
(a) What is the final velocity of sphere B?
(b) Was the collision elastic?
2. A grenade of mass 10 kg explodes into three pieces in the same plane, two of which, A (5.0 kg) and B
(2.0 kg), move off as shown. Calculate the velocity of the 3.0 kg third piece, C.
3.
Two cars were involved in a car accident. Car A of mass 1300 kg was travelling north
when it was hit by a 950 kg car going east on an intersecting street. The cars stuck
together and slid 19.4 m at [E60°N]. The speed limit on both streets was 70 km/h (19.4
m/s). Assume that momentum was conserved during the collision and that acceleration
was constant during the skid. The coefficient
of kinetic friction between the tires and pavement was 0.70. Were either of the cars
speeding?
Chapter 10 Test
Answer the following questions, showing any necessary calculations.
Fill in the blanks in the following questions.
1.
(a)
According to Newton’s ________ law, an object with no net force acting on
it remains at rest or in motion with a constant velocity.
(b)
Losing speed as you ride your bike uphill demonstrates Newton’s ________
law.
(c)
If you push against a wall, the wall pushes back against you with _______
force.
(d)
An object is in static equilibrium if ________________________________.
kg  m
s and _________.
Momentum can be expressed in the units
(e)
(f)
A/an _______________ force can change the momentum of a system so that
momentum is not conserved.
________________.
(g)
Energy transfer is at a maximum when the colliding objects have the
same __________.
(h)
When no external force acts on the system of particles, the system is considered
to be _____________.
(i)
All collisions conserve momentum, but not all collisions conserve
_______________.
Answer the following questions on a separate sheet of paper.
2.
If the weight of a balloon is 3000 N and the lift force provided by the atmosphere is 3300
N, in which direction is the net force acting?
3.
What is the tension in a rope that is supporting a 4.2 kg bucket?
4.
The coefficient of sliding friction between a 78 kg box and a warehouse floor is 0.21.
How much force is needed to keep the box moving at a constant velocity across the floor?
5.
You are pushing on a 65 kg crate with a horizontal force of 75 N. If you are moving the
crate at a constant velocity, what is the coefficient of friction between the crate and the floor?
6.
You are on an elevator that is travelling from the lobby to the top of a
building. As the elevator slows to a stop at the top floor, what happens to
the normal force?
7.
Suppose you pull on a rope tied to a large carton, but you cannot move the carton. What
forces are acting on your hand?
8.
An elevator with a mass of 1.10 × 103 kg accelerates upward at 0.45 m/s2. What
is the force acting on the elevator’s support cable?
9.
A 47 N box is pulled along a frictionless horizontal surface by a 25 N weight hanging
from a cord on a frictionless pulley.
(a)
What is the acceleration of the box and the weight?
(b)
What force is exerted on the cord?
10.
Two children are playing on a 2.0 kg seesaw. One child has a mass of 25 kg and sits 2.5 m from
the pivot point. How far away from the pivot point must the other child, whose mass is 20 kg, sit in order to
balance the seesaw? Assume that the pivot point is located at the centre of the seesaw.
11.
A person’s forearm and hand have a total mass of 2.0 kg with centre of gravity located 15 cm from
the elbow. In the person’s hand is a 5.5 kg mass, and the centre of gravity of the mass is located 35 cm
from the elbow. If the biceps muscle is attached 5.0 cm from the elbow, how much force must this muscle
exert in each situation?
(a)
the forearm and upper arm form an angle of 90°
(b)
the forearm and upper arm form an angle of 120°
12.
Two cars collide at an intersection and become entangled. Car A has a mass of 1200 kg and was
travelling south at 17 m/s. Car B has a mass of 900 kg and was travelling west. Skid marks indicated that
immediately after the collision, both cars moved at an angle of 39° south of west. Calculate the velocity of
car B before the collision.
11.3 BLM
Answer the following questions.
Circle the letter of the choice that best completes each statement.
1. The horizontal acceleration of a projectile ____________ as its position changes.
(a) increases
(b) decreases
(c) is constant
(d) is zero
2. The initial horizontal velocity of a projectile is ____________ its final
horizontal velocity.
(a) greater than
(b) less than
(c) equal to
3. The rising and falling times of a projectile are equal if the launching position is ____________ the
landing position.
(a) above
(b) below
(c) at the same height as
4. For a fast ball to pass the height of a batter’s chest, the pitcher must aim the ball ____________.
(a) exactly at the height of the batter’s chest
(b) slightly below the height of the batter’s chest
(c) just above the height of the batter’s chest
5. An object in circular motion travels a distance of ___________ during its period.
(b) 4 r
(a) r
2
(c)
2 r
(d)
2
r
Solve the following problems on a separate sheet of paper.
6. Two people are on a carnival ride that uses centripetal and frictional forces to hold its riders in place
inside a rotating drum. How do the velocity, acceleration, and force acting on the people differ if one
person has twice the mass of
the other?
7. A soccer player kicks a ball into the air at an angle of 36.0 o above the horizontal. The initial velocity
of the ball is 30.0 m/s. How long is the soccer ball in the air?
8. What is the horizontal distance travelled by the soccer ball in problem 7?
9. What is the maximum height reached by the soccer ball in problem 7?
10. A runner moving at a speed of 5.6 m/s rounds a curved track with a 65 m radius. What is the runner’s
centripetal acceleration?
11. A coin rolls along the top of a 1.33 m high desk with a constant velocity. It reaches the edge of the
desk and hits the ground 0.25 m from the edge of the desk. What was the velocity of the coin as it
rolled across the desk?
12. A 0.050-kg disk attached to the end of a 0.150 m wire revolves uniformly on a flat, frictionless
surface.
(a) If the disk makes three complete revolutions per second, what is the force exerted by the wire on
the object?
(b)
What is the speed of the disk?
13.1
Answer the following questions. Use a separate sheet of paper if necessary.
1. A 0.50 kg mass hung from a spring oscillates 3.0 times per second with an amplitude of 0.15 m.
Calculate
(a)
the speed when it passes the equilibrium position
(b)
the speed when the mass is 0.10 m from the equilibrium position
(c)
the total energy of the system
(d)
the equation describing the position of the mass, assuming that the maximum
amplitude occurs
at t = 0 s
2.
A 65 kg person causes the springs in a 1000 kg car to compress 2.8 cm vertically. What will be the
frequency of oscillation when the car goes over a bump?
3.
A block is suspended vertically by two identical springs at both ends. If the mass of the block is m
and the spring constant is k, what is the frequency of vibration?
4.
A 25.0 g bullet is fired at a 0.600 kg block attached to a horizontal spring. After impact, the bullet
and block oscillate with an amplitude of 21.5 cm. If the spring constant is 6.70  103 N/m, what was the
speed of the bullet before impact?
5.
Suppose a block of mass m is connected by two springs, one on either side of m. The spring
constant in one spring is k1 and in the other is k2. Both springs are attached to a fixed wall, and the mass–
spring system is laying horizontally on a frictionless surface. Show that the period of oscillation is given by
2
T=
12.5
m
k1  k2
Answer the following questions.
Circle the letter of the choice that best completes each statement.
1.
During its orbital period, as a planet moves closer to the Sun, the orbital velocity of the
planet ___.
(a)
increases
(b)
decreases
(c)
remains the same
2.
According to Newton’s law of universal gravitation, the force of attraction between any
two masses is directly related to the ___.
(a)
distance between the masses
(c)
velocity of the two masses
(b)
product of the two masses (d)
sum of the two masses
3.
As the distance between two bodies increases, the force of attraction between the bodies
___.
(a)
increases
(b)
decreases
(c)
remains the same
4.
Astronauts in an orbiting space shuttle experience a sensation of weightlessness because
___.
(a)
the space shuttle is falling freely toward Earth
(b)
the space shuttle is not affected by Earth’s gravity
(c)
the mass of the space shuttle decreases as the distance from Earth increases
(d)
the space shuttle is moving away from Earth
5.
The force of gravity exerts a ___ on an orbiting satellite.
(a)
balanced force (c)
tangential force
(b)
centripetal force (d)
all these choices
6.
In the diagram below, the pair of spheres that experiences the greatest force of attraction
is ___.
(a)
A and B (b)
B and C (c)
A and C
Answer the following questions on a separate sheet of paper.
7.
Explain why Kepler was able to use Tycho Brahe’s data about the positions of stars and
planets to develop his laws of planetary motion, while Brahe was unable to use the same data successfully.
8.
Earth is closer to the Sun in December than it is in July. What happens to the orbital
speed of the planet between July and December? Explain your answer.
9.
What would happen to the magnitude of the gravitational force between two bodies under
the following circumstances?
(a)
the mass of one of the bodies was doubled
(b)
the distance between the two bodies was doubled
10.
What information do you need to find the period of a planet using Kepler’s
third law?
11.
The mass of Jupiter is approximately 318 times that of Earth, yet the surface gravity of
Jupiter is less than three times the surface gravity of Earth. How do you account for this apparent
discrepancy?
12.
How does an artificial satellite remain in orbit at a constant distance from
Earth’s surface?
Answer the following questions, showing your calculations.
13.
Which of the pairs of masses below will have the greatest force of attraction between the
spheres?
14.
Two spheres, each having a mass of 20.0 kg, are positioned so that their centres are 8.00
m apart. What is the gravitational force between the spheres?
15.
What will be the force if the spheres described in question 14 are positioned with their
centres 4.00 m apart?
16.
If the mass of one of the spheres described in question 14 was doubled, how far apart
would the spheres have to be to maintain the same gravitational force between them?
17.
The distance between Earth and the Sun is often expressed as one astronomical unit
(AU). Using this unit, find the distance between the Sun and Mars, which has a period of approximately
686 Earth days.
14.6
Answer the following questions, showing all steps in your calculations.
1. A point charge of +9.0 C exerts a repulsive force of 0.60 N on a nearby point charge of magnitude
4.0 C.
(a) What is the sign of the second charge?
(b) How far apart are the two point charges?
2. Two identical objects have charges of – 4.0 nC and +8.0 nC. When they are a distance d apart, the
force between them has a magnitude of 3.0 N. The objects are touched together and then separated
again, this time by a distance of 0.5d.
(a) Was the original force attractive or repulsive? Give a reason for your answer.
(b) Was the final force attractive or repulsive? Give a reason for your answer.
(c) What is the magnitude of the final force?
3. Explain how the data in an experiment to verify Coulomb’s law can be analyzed to produce a straightline graph.
4. (a) List two ways in which electric, gravitational, and magnetic forces
are similar.
(b) List one way in which each force is different from the other two.
5. The gravitational field intensity on the surface of Jupiter is 26 N/kg. What gravitational force would a
4.0 kg object experience 2000.0 km above the surface of Jupiter? The radius of Jupiter is 7.18  107
m.
6. In the diagram, A and B represent small spherical charges of +56 C and
–34 C, respectively. What is the magnitude and direction of the
electric field intensity at point C?
7. (a) Sketch the gravitational field line pattern of Earth and the Moon, given that Earth has a mass that
is approximately 100 times that of the Moon.
(b) Explain how you might do a vector analysis at one point on a field line
to verify its direction, assuming that you had all relevant mass and
distance data.
8. Points A and B are 4.8 cm and 7.2 cm away from a point charge of –6.2 C
at point C. AC and CB are at right angles.
(a) How much work must be done in moving a 2.0 pC charge from A to B?
(b) What is the potential difference between points A and B?
(c) Which of these two points has the higher potential difference? Explain
your answer.
14.5
Solve the following problems, showing all steps in your calculations.
1. Calculate
(a) the electric field intensity at a point 15.2 cm from the centre of a spherical charge of +18.6 C
(b) the electric potential difference at this point
2. Charges A (–5.4 nC) and B (+8.2 nC) are located at two of the vertices of an equilateral triangle, with
sides that are 6.0 cm long. Determine
(a) the electric field intensity at the third vertex, C, of the triangle
(b) the electric potential difference at this point
3. A rectangle has a charge +5.0 C at vertex A, +8.0 C at vertex B, and –9.0 C at vertex C. Side AB
is 4.0 cm long, and side BC is 5.0 cm long. Calculate
(a) the electric field intensity at the fourth vertex, D
(b) the electric potential difference at the point of intersection of the diagonals of the rectangle
4. A charge of +6.8 C is 8.2 cm to the left of a charge of –5.4 C. Determine the location of any points
that are collinear with the two charges and have zero electric potential difference.
16.7
Answer the following questions in the space provided.
1.
A positive charge is travelling away from you into the page between two magnets, as shown in the
diagram. In which direction will the charge be deflected? ____
(a) left
(b) right
(c) up
(d) down
2.
The force on a current-carrying wire in a magnetic field is both ___ the direction of the magnetic field
and the direction of the current.
(a) parallel to
(b) opposite to
(c) at right angles to
(d) independent of
3.
Which one of the following actions produces attractive forces? ____
(a) bringing the north poles of two magnets together
(b) placing a current-carrying wire east-west above a compass
(c) placing two wires, with currents flowing in the same direction, parallel to one another
(d) pushing a wire between the ends of a horseshoe magnet
4.
Which description is accurate for a magnetic force experienced by a charged particle moving through
a magnetic field? _____
(a) The force is always greater than zero.
(b) The force is constant, regardless of the direction of the field.
(c) The force is at maximum when the particle’s velocity is parallel to the field.
(d) The force is at maximum when the particle’s velocity is perpendicular to the field.
16.5
Answer the following questions, providing diagrams where required.
1. Explain with the help of a labelled diagram the principle of electromagnetic induction.
2. Describe Faraday's coil experiment with the aid of a diagram.
3. What are the main parts of a DC generator? Draw a diagram showing voltage against time for a single
coil DC generator.
4. Name three factors that contribute to the amount of current produced by an electric generator.
__________________________________________________________________
__________________________________________________________________
5. Draw a diagram of an electromagnet showing the power source, the direction of the current, and the
north pole.
6. What is the purpose of the commutator in the DC generator?
__________________________________________________________________
__________________________________________________________________
7. A transformer has 100 turns in the primary coil and 10 000 turns in the secondary coil. If the input
voltage is 12 V, calculate the output voltage. What type of transformer is this?
__________________________________________________________________
8. If the power output of a transformer is 1200 watts and the current in the primary coil is 10 A, what
must be the voltage input?
__________________________________________________________________
18.3
4. A metallic surface with a work function of 1.0 eV is struck by a 497 nm photon. What is the
maximum kinetic energy of the emitted photoelectron?
(a) 0 eV
(b) 1.0 eV
(c) 1.5 eV
(d) 2.0 eV
(e) 2.5 eV
5. What is the longest wavelength of light that will emit electrons from a metal with a work function of
3.6 eV?
(a) 5.5  1026 m
(b) 3.8  1024 m
(c) 690 nm
(d) 175 nm
(e) 345 nm
6. What is the momentum of a 1.0  1015 Hz photon?
(a) 1.1  10–27 kg·m/s
(b) 2.2  10–27 kg·m/s
(c) 3.3  10–27 kg·m/s
(d) 4.4  10–27 kg·m/s
(e) 5.5  10–27 kg·m/s
19.3
Answer the following questions.
The following diagram applies to questions 1–3 and represents energy levels for a fictional element,
olympium.
energy
in eV
0
–1
ionization
n=4
–3
n=3
–6
n=2
–10
n=1
1. If the atom is excited to the n = 3 level, what are the possible wavelengths of the light emitted as the
atom returns to its ground state?
(a) 124, 177, and 414 nm
(b) 249, 311, and 414 nm
(c) 177, 311, and 414 nm
(d) 124, 249, and 311 nm
(e) 177, 249, and 311 nm
2. If the atom is struck by an 8 eV electron, what are the possible energies of the electron after the
collision?
(a) zero eV only
(b) 8 eV only
(c) 4, 7, and 8 eV
(d) 0, 1, and 8 eV
(e) 1, 4, and 8 eV
20.5
Answer the following questions on a separate sheet of paper. Show all calculations.
1.
2.
atom?
57
26
Fe with a mass of 56.935 396 u.
(a)
Calculate the mass defect of
(b)
Determine the binding energy per nucleon, in MeV, for
The binding energy per nucleon for
57
26
Fe .
208
82
Pb is 7.93 MeV. What is the atomic mass of this
3.
Write the nuclear equation for the transmutation of a radioactive uranium isotope,
by the emission of an alpha particle.
234
92
24
4.
The half-life for 11Na is 15 h. How many grams of sodium would remain after
75 h if 30 g were in the original sample?
3
5.
If 1 H has a half-life of 12.5 a, how many years have passed when only 1/64 of the
original mass remains?

U,