All Take Home quizzes Summer 2021.pdf
June th, 20Name____________________
QUIZ#6, Due in class on , J
Instructions.
1) Open Book, Open notes, Open mind.
2) Answer all questions and show all calculations.
No credit will be given if there are no calculations.
QUIZ on Chapter 6 Friction, Uniform Circular motion of a ca
On a evening, a is driving along a straight, level road
at 5 m/s. The driver panics when a deer runs onto the road and
locks the wheels while
aking. If the coefficient of friction fo
the wheel
oad interface is 0. , how
?
A
A
A 00-kg car along a straight portion of at a constant velocity
of m/s, due . The car then encounters an unbanked of radius
0 m. The car follows the curve traveling at a constant speed of m/s
while the direction of the car changes from to south.
the magnitude of the frictional force between the
tires and the road as the car negotiates the un banked curve
. Block A has a mass .0 kg and
lock B has a mass 4 kg. The two blocks are connected by a very light rope of
negligible mass that passes over a pulley as shown. The coefficient of kinetic
friction for the blocks on the ramp is 0. . The ramp is angled at = 45 .
At time = 0 s, block A is released with an initial speed of .0 m/s. What is the
tension in the rope?
All Take Home quizzes Summer 2021.pdf
June , 20Name____________________
Quiz#5, Due in class on , June
Instructions.
1) Open Book, Open notes, Open mind.
2) Answer all questions and show all calculations.
No credit will be given if there are no calculations.
QUIZ on Chapters 5,13 Forces, Friction and Gravitation
A -kg car down a straight, level road at a constant
speed of . When the driver sees a police cruiser ahead, she removes
her foot from the accelerator.
, he magnitude acting on the car
during th
ases show
In which case will the magnitude of the normal force on the box
:
(i) the book is at rest, (ii) the book is
Under which of these conditions is the book in equili
ium?
A block of mass is hung by ropes as shown. The system is in
equili
ium. The point O represents the knot, the junction of the three
opes. the
magnitudes of the
A force pushes a block of mass , which in
turn pushes a block of mass as shown. The blocks are
accelerated across a horizontal, frictionless surface. What is the
magnitude of the force that the block exerts on the
lock?
Two are
gravitational force between
these two objects
Your weight is . What would you
o
iting the in the Space Shuttle at an altitude of 00 km?
PowerPoint Presentation
Problem#1, 5 points
Express the result of the following calculation, to the proper number of significant figures:
41.314*11.30 – 7866. x 10-3 =
22.6
Test 1, PHY 251. Name______________________
Units, Translational and Rotational Kinematics, Vectors, Projectile motion, relative motion,
Newton’s Laws, Universal Law of Gravitation.
Instructions.
1) Open book, Open notes, Open mind.
2) Answer all questions and show all calculations. No credit will be given if there are no
calculations.
3) The Take Home test is due back on June 28th at 10:00 PM (submit on Moodle or by e-mail).
6/21/21
Problem#2, 10 points
Two objects are thrown from the cliff above the ground at the same time.
First object is thrown up, and the second object is thrown down, both with the same
initial speed of 30 m/s. Assume no air resistance.
The object thrown down hits the ground in 5 seconds.
a) Draw a sketch showing datum where initial position for each object is zero. Show which
direction is positive in your calculations for each object.
) Find height of the cliff.
c) What vertical distance does the object thrown up cover at the time when the object thrown
down hits the ground?
d) What is the maximum height reached by the object thrown up?
Problem#3, 15 points
A car starting from rest moves with constant acceleration of 3.0 m/s2 for 20 s, then travels
with constant speed for another 20 s, and then finally slows to a stop with constant
deceleration Of 4.0 m/s2.
a) Draw a sketch showing datum where initial position of the car is zero. Show which
direction is positive in your calculations.
) Plot car’s position vs time for the entire trip.
c) Plot car’s velocity vs time for the entire trip.
d) Use the plot of velocity vs. time graph to find car’s displacement for the entire trip.
(Hint: v = dx/dt, so Displacement = ∫vdt, which is the area under the velocity vs time curve).
e) Find the total distance car traveled for the entire trip.
f) Find average velocity (magnitude and direction) of the car after 40 seconds.
g) Find average speed for of the car after 20 seconds.
Problem#4, 10 points
Three vectors, expressed in Cartesian coordinates, are as shown below in meters:
a) Add vectors S, T, U graphically (use the scale 1 m = 1 cm).
) Find the magnitude and direction of the resultant vector S + T + U analytically.
Problem#5, 5 points
Given Vectors A = 5i -7j and B = -3i + 10j
a) Sketch both vectors in the same coordinate system.
) Use the definition of Vector Dot Product to find an angle between the two vectors.
Problem#6, 10 points
A football is hit from ground level with an initial speed of 22 m/s at an angle of 430
above the horizontal. The Coordinate system with datum is shown below.
(a) Determine the time when football reaches its maximum height.
(b) Find the maximum height reached by the football.
(c) Calculate the magnitude and direction of the football’s velocity vector right before
impact with the ground at landing. Show it on the sketch below.
(d) What are the horizontal and vertical components of the football’s acceleration
vector at the maximum height?
(e) What is the range of horizontal travel?
Problem#7, 10 points
A small airplane is flying with a constant speed of 260 miles per hour relative to the wind as
shown in the sketch below.
However, wind has the speed of 45 miles per hour and blows in the direction shown.
It takes 70 seconds for the plane to fly over the river 4 miles long.
a) Draw a vector diagram showing Velocity of the Plane with respect to the
observer on the ground.
) Find the angle Ï´.
4 miles
Rive
Problem#8, 10 points
A block (mass = 2 kg) slides from rest down an inclined plane (no friction)
thru a distance of 3 meters. The plane makes an angle θ = 400 with the horizontal.
a) Draw Free Body Diagram of the block. Label datum, coordinate system, and sign
convention for the positive direction of motion.
) What is the block’s apparent weight?
(Hint: Apparent weight is the perpendicular force from the ramp into the block)
c) Use Newton’s Laws of Motion to calculate the block’s acceleration.
d) Calculate the final velocity of the block after traveling 3 meters down the plane.
e) Find the time it takes the block to travel 3 meters down the plane.
Problem#9, 10 points
Boxes shown below are connected by a cord running over a pulley. Box I of mass
9.0 kg on the top of the table. Box II has a mass of 16.0 kg.
Assume no friction between box I and the Table. The box I is pushed to the right with the
Initial velocity of 3 m/s.
(a) Draw free-body diagrams for the two boxes. Show all the forces acting on each box.
Also show datums, coordinate system and positive direction of motion for each box.
(b) Calculate the acceleration of the system, and of each box.
(c) Calculate the tension in the cord.
(d) Is tension in the cord equal to the weight of the box II? Explain using Newton’s 2nd law.
(e) Find the distance the box II will fall in 1.5 seconds after the block I is pushed.
Problem#10 10 points
Originally a fishing rod line is pulling the fish out of the water with the speed of 7.4 m/s.
Then the fishing rod wheel of diameter 38 cm rotating clockwise is slowed down to a stop
with constant acceleration.
The fish is pulled thru distance of 100m until the wheel stopped rotating.
a) For the linear speed of 7.4 m/s of a point on the rim of a wheel, find angular velocity
of the wheel (magnitude and direction).
) Calculate centripetal acceleration of the point on the wheel’s rim (Magnitude and
direction), when the linear speed of a point on the rim of a wheel is 5.0 m/s.
c) What is the angular acceleration of the wheel (Magnitude and direction) as it slows down?
d) How many revolutions will the wheel complete by the time it will come to the stop?
e) Calculate time required for the wheel to stop.
Problem#11 5 points
An object weighs 500 N on the surface of the Moon. The Moon has radius r. The object is
aised to a height of 3r above the Moon's surface.
a) Draw free body diagram of the object.
) Use Universal Law of Gravitation to calculate gravity at the Moon surface.
Moon’s diameter = 3,476 km, Moon Mass = 7.3 * 1022 kg
c) Calculate the object’s weight at the new location, 3r above the Moon’s surface.
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