Physics 1500
Ex02.REDO
Ex02.REDO
Physics 2610 Ex02.REDO Ch XXXXXXXXXXSpring
March 9, 2021 Tuesday
Name ____________________________________
Doing a redo exam is optional, not required. To receive any credit for each problem,
you must give the equation to use, substitute in in the right numbers needed, and
have a co
ect numerical result (no credit otherwise).
Extra credit will be calculated by taking the difference between your redo score and
your original score and multiplied by an extra credit fraction of 0.25. For example, if
your redo score is 30 points higher than your original score, this would give you 7.5
points extra credit.
If you choose to take this option, turn in a hard copy of your redone exam and
include a Xerox copy of your original exam. Redone exams must be turned in
as a hard copy, I will not accept electronic redo exams sent in by email (all
emailed copies will be deleted and ignored). This option will be available until two
weeks before finals week begins. There will be no redo exam for the planned fourth
exam since it will be close to finals week.
Problem-solving strategy for maximum credit:
• Show your problem-solving methods and steps, show the details of your calculations. The steps showing the
details of your work counts for most of the credit assigned to each problem. If you give just the numerical answer
to the problem, you will receive minimal to no credit, so please show all your work.
• Include sketches as needed.
• Express your answers with proper units and significant figures.
• If you are unable to a find an answer needed in a multi-part problem, for partial credit state a logical estimate
you will use for the needed quantity to complete the problem.
Ex02.REDO
Ex02.REDO
1. A 8.00 kg steel ball is suspended by a light string from the
ceiling. A constant horizontal force F directed to the right, keeps
the ball in static equili
ium when the string is at angle θ = 35.0°
from the vertical as shown. Draw a FBD for the ball.
a) Determine the tension force in the string.
) Determine the value of the horizontal force F that keeps the ball in static equili
ium as shown.
2. A block of mass m1 = 4.50 kg is being pulled to the left by a
horizontal force F = 95.0 N on a frictionless horizontal table
surface, and is connected to a light string that passes over a light
frictionless pulley fastened to a hanging block of mass
m2 = 7.50 kg. Draw free body diagrams for both blocks, you can
put these on the figure.
a) Find the magnitude of the acceleration of the blocks.
) Find the tension in the string.
c) If the initial velocity of the block is 1.50 m/s left, what is its velocity after 2.75 s?
θ
F
m2
m1F
v
Ex02.REDO
Ex02.REDO
3. A block with mass 5.50 kg is moving up a ramp with some
initial velocity v as shown. The ramp is inclined at an
angle θ = 20.0° above the horizontal. An applied force F =
75.0 N is acting on the block and is directed up the ramp
parallel to the ramp’s surface as shown. The coefficient of
kinetic friction between the ramp’s surface and block is
0.300. Draw a free body diagram for the block, you can
put this on the figure.
Determine the acceleration of the block.
4. Consider a child of mass m = 35.0 kg riding a Fe
is
Wheel that moves in a vertical circle of radius R = 7.50 m
at a constant speed of 5.00 m/s. Draw free-body-diagrams
for the child at the top and bottom of the ride.
a) Determine the normal force exerted by the seat on the child
at the bottom of the ride.
) Determine the normal force exerted by the seat on the child
at the top of the ride.
c) Determine the maximum speed of the Fe
is Wheel that allows the child to still remain in his seat at
the top of the ride.
m
θ
Ex02.REDO
Ex02.REDO
5. A woman whose mass is 55.0 kg stands on a spring scale in an elevator of a tall building. The elevator is
at the top floor of the building and is preparing to descend to the lowest floor. Starting from rest the
elevator descends at a rate of 3.25 m/s2 until attaining a constant speed of 6.25 m/s. It travels with this
constant speed downwards as it approaches the lowest floor. The elevator then slows down undergoing a
uniform acceleration upward of 2.75 m/s2 until coming to rest at the lowest floor.
a) What does the spring scale register during the first time interval as the elevator descends at a rate of
3.25 m/s2 ?
) What does the spring scale register during the second time interval as the elevator travels at a
constant speed of 6.25 m/s downwards ?
c) What does the spring scale register during the final time interval as the elevator slows down
undergoing a uniform acceleration upward of 2.75 m/s2 until coming to rest at the lowest floor?
6. A force F = (–5 i + 2 j) N acts on a particle that undergoes a displacement r = (–3 i + 6 j) m.
a) Find the work done by the force on the particle
) Find the angle between F and r.
Ex02.REDO
Ex02.REDO
7. Consider a block of mass m = 12.5 kg on a horizontal
frictionless surface. The block is pulled a distance
d = 4.50 m to the right. A force F1 = 40.0 N acts on the
lock at an angle θ = 36.87° with the horizontal. Another
force F2 = 11.0 N also acts on the block and is directed
horizontally to the left. Draw a FBD for the block clearly
labeling all the forces, including vertical, acting on it.
a) Having been pulled a distance d, what is the work done by the normal force on the block?
) Having been pulled a distance d, what is the work done by gravitational force on the block?
c) Having been pulled a distance d, what is the work done by the force F1 on the block?
d) Having been pulled a distance d, what is the work done by the force F2 on the block?
e) Taking into account the net work done by all the forces acting on the block, if the block begins with an initial
velocity of 2.50 m/s to the right, determine its velocity after being pulled the distance d to the right as depicted
in the figure by using the net-work kinetic energy principle.
8. A 7.00 kg rock is sitting on the top edge of a cliff 50.0 m above ground level below. Let the base of the
cliff at ground level be the zero configuration for gravitational potential energy of the rock-Earth system.
a) Find the potential energy of the rock when it is sitting on the top edge of the cliff.
) The rock falls off the cliff to the ground below. Determine the change in potential energy of the rock.
c) Determine the work done by the gravitational force on the rock as it falls from the top of the cliff to
the ground below.
d
m
F1
θF2
Physics 1500
Ex02.REDO
Ex02.REDO
Physics XXXXXXXXXXEx03.REDO Ch XXXXXXXXXXSpring
Given on April 9, 2021 Friday
Name ____________________________________
Doing a redo exam is optional, not required. To receive any credit for each problem,
you must give the equation to use, substitute in in the right numbers needed, and
have a co
ect numerical result (no credit otherwise).
Extra credit will be calculated by taking the difference between your redo score and
your original score and multiplied by an extra credit fraction of 0.25. For example, if
your redo score is 30 points higher than your original score, this would give you 7.5
points extra credit.
If you choose to take this option, turn in a hard copy of your redone exam and
include a Xerox copy of your original exam. Redone exams must be turned in
as a hard copy, I will not accept electronic redo exams sent in by email (all
emailed copies will be deleted and ignored).
Problem-solving strategy for maximum credit:
• Show your problem-solving methods and steps, show the details of your calculations. The steps showing the
details of your work counts for most of the credit assigned to each problem. If you give just the numerical answer
to the problem, you will receive minimal to no credit, so please show all your work.
• Include sketches as needed.
• Express your answers with proper units and significant figures.
• If you are unable to a find an answer needed in a multi-part problem, for partial credit state a logical estimate
you will use for the needed quantity to complete the problem.
Ex02.REDO
Ex02.REDO
1. Consider a spring, block and track system as shown.
a) The block of mass m = 5.00 kg is held at rest at point A against a spring whose spring constant
k = 1300 N/m which is compressed a distance x = 0.400 m from its equili
ium position. Determine
the potential energy stored in the spring.
) The block is released, the spring pushes the block to the right. If the spring is fully uncompressed
when the block reaches point B determine