Question 1
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A 0.200 kg dart is fired horizontally at a speed of 2.75 m / s when it hits a 0.700 kg block
... [Show More] ofwood
suspended by a string. The nose of the dart sticks into 0.00210 m the wood.
Together the dart and block swing upwards from a height of 0.0500 m above a table to
0.128 m above the table. Which of the following is the average force the dart applies to the
block during impact?
Select one:
a. 32.4 N
b. 15.1 N
c. 1.36 N
d. 0.872 N
Straighterline PHY250 General Physics I Midterm Exam (New Version June 2024)
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PHY250_TW | Chapter 7: Force of Gravity
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Grade 195.00 out of 200.00 (98%)Question 3
Correct
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Which is the standard unit of time in the metric system?
Select one:
a. minute
b. second
c. year
d. hour
Question 4
Correct
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of 5.00
An automobile of mass 900 kg is moving at a speed of 12.5 m/s when it encounters a hill.
At the bottom of the hill the car speed increases to 14.6 m/s. If the elevation of the hill is
15.3 m, how much work did the brakes do while going down the hill?
Select one:
a. -1.09x105 J
b. -9.59x104 J
c. 2.05x105 J
d. 1.33x105 J
A bicyclist is heading east along a straight bike path. As the path crosses into a state park,
it turns from dirt to pavement and the biker accelerates at a constant rate of 1.2 m / s2. At
time t = 0 the bicyclist is 2.0 m east of the state park line and is going at a speed of 3.0 m /
s. Where is the cyclist when his velocity is 10.0 m / s?
Select one:
a. 38 m from the state line
b. 40 m from the state line
c. 5.8 m from the state line
d. 8.3 m from the state line
Question 2
Correct
5.00 points out
of 5.00The moment of inertia of a thin rectangular sheet of uniform mass density about an axis
running through its center, as shown, is ICM = 1 M(A2 + B2), where M is the total
12
mass of the sheet and A and B are its length and width. What is the moment of inertia of
the sheet about one of its corners? (The axis of rotation is still perpendicular to the sheet.)
Select one:
a. 7 M(A2 + B2)
12
b. 13 M(A2 + B2)
12
c. 1 M(A2 + B2)
3
d. 1 M(A2 + B2) + 1 M√A2 + B2
12 2
Question 5
Correct
5.00 points out
of 5.00Question 7
Correct
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An airplane travels 600 m down a runway for take off. It starts from rest and moves with
constant acceleration. It is in the air in 23 s. What is its speed when it takes off?
Select one:
a. 7.2 m / s
b. 2.3 m / s
c. 52 m / s
d. There is not enough information provided to answer the question.
A 3000 kg satellite is in a circular orbit around the Earth. The radius of the orbit is r0. Using
the energy diagram, what is the value of r0? The mass of the Earth is 6 × 1024 kg.
Select one:
a. 7.8 × 103 m
b. 6.0 × 103 m
c. 7.8 × 107 m
d. 6.0 × 107 m
Question 6
Correct
5.00 points out
of 5.00Question 9
Correct
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of 5.00
Which of the following is an example of uniform circular motion?
Select one:
a. the planet Pluto in its wandering about the Sun
b. the swing of a pendulum between the turning points
c. a bug sitting still on a playing 45 rpm record
d. the weights on the rim of a car tire as the car slowly accelerates
Kylie throws Kyra a kiwi. The kiwi leaves Kylie’s hand at a height of 1.3 m from the ground
and Kyra grabs it out of the air at a height of 1.6 m. Kylie throws the kiwi at an angle of 33°
relative to the horizontal. The kiwi is in the air for 1.1 s. How far apart are Kylie and Kyra
standing? (Assume there is no drag force that no wind is blowing.)
Select one:
a. 9.4 m
b. 9.6 m
c. 5.4 m
d. 7.1 m
Question 8
Correct
5.00 points out
of 5.00Question 11
Correct
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of 5.00
A 1,450 kg car moves with a speed of 25.0 m / s when it collides with a stationary car having
a mass of 1,550 kg. The two vehicles lock bumpers on impact. The two cars thencollide
with a stationary third car of mass 1,250 kg. During this second impact, the third vehicle
becomes attached to the second but the first car is breaks free and moves at
0.125 m / s in the opposite direction. Which of the following is the final velocity of thesecond
and third cars after the final collision?
Select one:
a. 12.88 m / s
b. 12.14 m / s
c. 14.42 m / s
d. 13.01 m / s
Which of the following is the resultant gravitational force acting on the 100 kg mass in the
diagram?
Select one:
a. 7.4 × 10−7 N
b. 8.2 × 10−7 N
c. 1.56 × 10−6 N
d. 15.6 × 10−6 N
Question 10
Correct
5.00 points out
of 5.00Question 13
Correct
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of 5.00
Sally in St. Louis, MO gets a call on her cellular phone from Cindy in Cincinnati, OH, who
invites her to go to a Reds baseball game. The cellular signal travels through a satellite
that is in geosynchronous orbit exactly half way between St. Louis and Cincinnati at a
height of 36,000 km above the Earth’s surface. The next day, Sally gets in her car and
drives to Cincinnati where she watches the game. There are approximately 600 km
between St. Louis and Cincinnati. What is the difference between Sally’s displacement
and the displacement of the cellular signal?
(Assume that St. Louis and Cincinnati are at the same height above sea level.)
Select one:
a. There is no difference in the displacement of the cellular signal and Sally’s
displacement.
b. The displacement of the cellular signal is the opposite of Sally’s displacement.
c. The displacement of the cellular signal is approximately 200 km more than the
displacement of Sally.
d. Sally’s displacement is about 40 km more than the displacement of the cellular
signal.
How can you calculate the magnitude of a vector using scalar products?
Select one:
a. Multiply it by a unit vector.
b. Multiply it by itself and take the square root.
c. Multiply it by a known vector.
d. Multiply it by a scalar number.
Question 12
Correct
5.00 points out
of 5.00Question 15
Correct
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of 5.00
The distance along both the axes, as shown in the drawing below, are in meters. Which of
the following is the resultant gravitational force vector acting on the 100 kg mass at the
origin of the diagram?
Select one:
a.
1.3 × 10−3 N at + 85∘
b.
1.3 × 10−3 N at − 85∘
c.
1.1 × 10−4 N at + 85∘
d.
1.1 × 10−4 N at − 85∘
Which of the following is the sign of the scalar product of two vectors that have an angle of
79° between them?
Select one:
a. It cannot be determined without more information
b. zero
c. positive
d. negative
Question 14
Correct
5.00 points out
of 5.00Question 17
Correct
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of 5.00
The work done to accelerate a car from 0 m / s to 40 m / s is times greater than the
work done to accelerate it from 0 m / s to 20 m / s?
Select one:
a. two
b. three
c. four
d. eight
Which of the following is involved in uniform circular motion?
Select one:
a. constant tangential velocity
b. constant angular velocity
c. zero acceleration
d. net tangential acceleration
Question 16
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5.00 points out
of 5.00Question 19
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Using Kepler’s third law of planetary motion, how many times larger is the average radius
of Neptune’s orbit if it takes 164 Earth-years to orbit the Sun? Approximate each orbit as
being circular.
Select one:
a. 164 times larger
b. 82 times larger
c. 30 times larger
d. 5.5 times larger
A force is applied to an object as shown. What is the direction of the torque vector?
Select one:
a. the same as the direction of the force vector
b. the same as the direction of the position vector
c. out of the screen
d. into the screen
Question 18
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5.00 points out
of 5.00Question 21
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Which of the following is the gravitational force between the Earth and the Moon? The
Earth's mass is 6 × 1024kg the Moon's mass is 7.4 × 1022 kg and the distance between
their centers of mass is 3.8 × 108 m.
Select one:
a. 2.6 × 1021 N
b. 2.1 × 1020 N
c. 7.5 × 1024 N
d. 7.8 × 1028 N
An empty freight train car of mass 10,000 kg is rolling along a level section of track at 2.00
m / s. It collides with a loaded car of weight 1.96 × 105 N, which is at rest. The cars couple
upon collision. Which of the following is the speed of the train after the collision?
Select one:
a. 1.02 m / s
b. 0.667 m / s
c. 2.00 m / s
d. 3.02 m / s
Question 20
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5.00 points out
of 5.00Question 23
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→
Why is A ⋅ B = AxBx + AyBy
→
Select one:
a. It isn’t.
b. All the cross-terms are equal to zero.
c. The vectors are 90° apart.
d. The vectors are pointing in the same direction.
These two systems each consist of two masses connected by ideal massless rods to a
fixed pivot point. The masses in the two systems are all identical, but the rods in the
second system are twice as long as the rods in the first. Suppose that both systems are let
go from rest. The instant after they are let go, the upper masses of each system have an
instantaneous acceleration vector, as shown. How do the magnitudes of these vectors
compare?
Select one:
a. 2a1 = a2
b. a1 = a2
c. a1 = 2a2
d. a1 = 4a2
Question 22
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5.00 points out
of 5.00Question 25
Correct
5.00 points out
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A 309 g glass rolls down an incline and onto a horizontal platform where it hits a beverage
can that is laying at rest on its side. The top of the incline is 11.0 cm above the horizontal
platform. The beverage can is initially at rest and weighs 7.35 N. Which of following is the
final velocity of the glass?
Select one:
a. 0.612 m / s
b. −5.83 m / s
c. −1.35 m / s
d. −0.612 m / s
Question 26
Correct
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At which of the following speeds would you have to throw a ball if you wanted it to reach a
maximum height of 10 m above the point you released the ball? Assume you throw it at a
70° angle with respect to the horizontal.
Select one:
a. 5 m / s
b. 14.8 m / s
c. 50 m / s
d. 208 m / s
From the following choices select the one that is not required for making quantitative
statements about the world.
Select one:
a. a regional unit system
b. units
c. standards of measurement
d. measurements
Question 24
Correct
5.00 points out
of 5.00Question 28
Correct
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of 5.00
Which of the following statements concerning friction is incorrect?
Select one:
a.
The force that prevents two surfaces from sliding across one another is called static
friction.
b.
The force of static friction ( fs ) between parallel surfaces in contact is given by: fs =
μsN.
c.
Sliding or kinetic friction is the force which acts to stop two surfaces from sliding past
one another.
d.
The force of kinetic friction acts opposite to the direction of motion and is expressed
by the following equation: fk = μkN.
A person with mass m is on a ride in an amusement park. She is accelerated by a vertical
wall with an acceleration of →a and her feet are not touching the floor. Ignoring air
resistance, the normal force must be equal to .
(Acceleration due to gravity is →g and t is the angle between the normal force and m→g .)
Select one:
a. m
→g
b. m→a
c. m
→
g sin t
d. m→g cos t
Question 27
Correct
5.00 points out
of 5.00Question 30
Correct
5.00 points out
of 5.00
A mass m is dropped from rest to the ground from a height h. Which of the following is
correct?
Select one:
a. When it strikes the ground, the speed of the mass is inversely proportional to h.
b. The kinetic energy of the mass when it strikes the ground is inversely proportional
to h.
c. The kinetic energy of the mass when it strikes the ground is independent of m.
d. When it strikes the ground the speed of the mass is independent of m.
Question 31
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A steel playground slide is 4.58 m long and is raised up 2.35 m on one end. Which of the
following is the final speed of a child of mass of 22.8 kg as she slides down from the top
starting at rest? Assume that there is minimal friction between the child and the slide.
Select one:
a. 9.47 m/s
b. 6.79 m/s
c. 4.86 m/s
d. 6.61 m/s
A car of mass m drives along a road. The road exerts a frictional force on each of the tires
equivalent to f. The frictional force of air resitance R exerts a backwards force on the car.
Assuming these are the only two forces in the horizontal direction, under which of the
following relationships would the car move at a constant speed?
Select one:
a. 4 f = R
b. ma − R = f
4
c. f = N − g cos θ
d. = mg
f 2
e. None of the above
Question 29
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5.00 points out
of 5.00Question 33
Incorrect
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If A + B = C , which of the following is not true?
→ → →
Select one:
→
a. |A | + |B | = |C |
→ →
→
b. |A + B | = |C |
c. A2 + B2 = C2
→ →
d. Ax + Bx = Cx
Question 34
Correct
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True or false?
Clockwise rotations are always positive.
Select one:
a. false
b. true
A spaceship is in space and currently at rest. The directive is given to accelerate from rest
to a speed of 2.90 × 103 m / s. If the fuel budgeted for this action is 400 kg, which of the
following is velocity of the exhaust gas required if the ship mass is 7.38 ×103 kg?
Select one:
a. 955 [m / s]
b. −955 [m / s]
c. –5.5 × 104 [m / s]
d. −1.01 × 103 [m / s]
Question 32
Correct
5.00 points out
of 5.00Question 36
Correct
5.00 points out
of 5.00
Which of the following is correct concerning the centripetal acceleration of an object in
uniform circular motion?
Select one:
a. The centripetal acceleration is directed radially outward.
b. The centripetal acceleration is in the tangential direction.
c. The centripetal acceleration is directed radially inward.
d. The centripetal acceleration is constant throughout the path of the uniform circular
motion.
Question 37
Correct
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Assume that when the brakes are applied a constant frictional force is exerted on the
wheels of a car. Which of the following is correct?
Select one:
a. The car loses kinetic energy at a constant rate.
b. The distance the car travels before coming to rest is proportional to the speed of the
car just before the brakes are applied.
c. The distance the car travels before coming to rest is proportional to the square of
the speed of the car just before the brakes are applied.
d. The kinetic energy of the car is inversely proportional to the time, with t = 0 being
the instant the brakes are applied.
In which of the following high speed collisions does the car experience a smaller force
than the other object participating in the collision?
Select one:
a. a car and a tractor trailer
b. a car and a bridge support
c. a car and the planet mars
d. none of the other choices
Question 35
Correct
5.00 points out
of 5.00Question 39
Correct
5.00 points out
of 5.00
A truck that weighs 1000 N moves at 5.89 m / s when it hits another vehicle in an elastic
collision. The second vehicle, weighing 981 N, was stationary but free to move. Find the
final velocity of the second vehicle after the collision.
Select one:
a. v2 f = 29.2 m / s
b. v2 f = 5.95 m / s
c. v2 f = 0.0583 m / s
d. v2 f = 58.3 m / s
The motor of a toy train quits when the train reaches the top of the far left hill in the
diagram. When the train of mass of 7.62 kg gets to the top of this hill, it is moving at a
speed of 0.100 m/s. When the train finally makes it up the last hill, it uses all of its
available mechanical energy to compress the spring. Which of the following is the distance
the spring compresses if the spring constant is 1.00 × 105 N/m.
Select one:
a. 0.0271 m
b. 0.000 m
c. 0.0119 m
d. 0.0192 m
Question 38
Correct
5.00 points out
of 5.00A particle free to move in one dimension is in stable equilibrium at x = a. Which of the
following might be a graph of the net force on the particle as a function of position?
Select one:
a.
b.
c.
Question 40
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