Test 5 Practice - Honors Physics, section HF1 Web Assign PDF

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Honors Physics, section HF1 INSTRUCTOR

Tara Weinstein

Test 5 Practice (Homework)

Dwight-Englewood HS, NJ

Current Score

QUESTION

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10

POINTS

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11

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15

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16

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17

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18

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TOTAL SCORE

–/322

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Due Date

WED, JAN 15, 2020 3:25 PM EST Request Extension

Description

Assignment Submission & Scoring Assignment Submission For this assignment, you submit answers by question parts. The number of submissions remaining for each question part only changes if you submit or change the answer. Assignment Scoring Your last submission is used for your score.

–/3 points

1.

SerCPAP11 7.P.001.

My Notes

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My Notes

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My Notes

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Convert 49.0° to radians, 17.0 rad to revolutions, and 70.5 rpm to rad/s.

(a) 49.0° to radians rad (b) 17.0 rad to revolutions rev (c)

70.5 rpm to rad/s rad/s

–/3 points

2.

(a)

SerCPAP11 7.P.001.OP.

Convert 46.0° to radians. rad

(b)

Convert 16.0 rad to revolutions. rev

(c)

Convert 71.5 rpm to rad/s. rad/s

–/2 points

3.

SerCPAP11 7.P.002.

A bicycle tire is spinning clockwise at 2.20 rad/s. During a time period Δt = 2.50 s, the tire is stopped and spun in the opposite (counterclockwise) direction, also at 2.20 rad/s. Calculate the change in the tire's angular velocity Δω and the tire's average angular acceleration αav . (Indicate the direction with the signs of your answers.)

(a)

the change in the tire's angular velocity Δω (in rad/s) rad/s

(b)

the tire's average angular acceleration αav (in rad/s2 ) rad/s2

–/2 points

4.

SerCPAP11 7.P.003.

My Notes

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The tires on a new compact car have a diameter of 2.0 ft and are warranted for 65,000 miles. (a)

Determine the angle (in radians) through which one of these tires will rotate during the warranty period.< rad

(b)

How many revolutions of the tire are equivalent to your answer in (a)? rev

–/2 points

5.

SerCPAP11 7.P.003.OP.

My Notes

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A new midsize car has tires with a diameter of 25.4 inches. The tires have a tread-life warranty of 61,000 miles. (a)

How many radians will the tires rotate through within the full warranty length? rad

(b)

How many revolutions is this equivalent to? rev

–/2 points

6.

SerCPAP11 7.P.004.

My Notes

A potter's wheel moves uniformly from rest to an angular speed of 0.20 rev/s in 25.0 s. (a)

Find its angular acceleration in radians per second per second. rad/s2

(b)

Would doubling the angular acceleration during the given period have doubled final angular speed? es o

Ask Your Teacher

SerCPAP11 7.P.004.OP.

–/2 points

7.

(a)

My Notes

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A large rotating turntable uniformly increases in angular speed from rest to 0.210 rev/s in 27.0 s. What is its angular acceleration in radians per second per second? rad/s2

(b)

The same turntable again starts from rest and accelerates uniformly in the same time interval, but now the angular acceleration is double that found in part (a). What is true about the final angular speed? is half the value given in part (a). is quadruple the value given in part (a). is double the value given in part (a). is the same as the value given in part (a).

SerCPAP11 7.P.005.

–/2 points

8.

My Notes

A dentist's drill starts from rest. After 3.50 s of constant angular acceleration it turns at a rate of 2.85

Ask Your Teacher 4 rev/min. 10

(a) Find the drill's angular acceleration. rad/s2 (b) Determine the angle (in radians) through which the drill rotates during this period. rad

–/2 points

9.

SerCPAP11 7.P.005.OP.

My Notes

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A power drill starts from rest and undergoes uniform angular acceleration for a period of 0.135 s until it turns at a rate of 2.45 (a)

104 rev/min. What is the drill's angular acceleration (in rad/s2 )? (Enter the magnitude.) rad/s2

(b)

What is the angle (in radians) through which the drill rotates during this period? (Enter the magnitude.) rad

–/1 points

10.

SerCPAP11 7.P.006.

My Notes

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A centrifuge in a medical laboratory rotates at an angular speed of 3,450 rev/min. When switched off, it rotates through 48.0 revolutions before coming to rest. Find the constant angular acceleration (in rad/s2 ) of the centrifuge. rad/s2

–/2 points

11.

SerCPAP11 7.P.006.OP.

My Notes

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A centrifuge in a biochemistry laboratory rotates at an angular speed of 3,800 rev/min, clockwise (when viewed from above). When switched off, it rotates through 54.0 revolutions before coming to rest. Assuming it is constant, what is the magnitude of angular acceleration (in rad/s2)?

rad/s2 What is the direction of the angular acceleration (again, when viewed from above)?

ockwise ounterclockwise he magnitude is zero.

–/4 points

12.

SerCPAP11 7.P.007.

My Notes 2

Ask Your Teacher

A bicyclist starting at rest produces a constant angular acceleration of 1.20 rad/s for wheels that are 37.5 cm in radius.

(a)

What is the bicycle's linear acceleration (in m/s2 )? (Enter the magnitude.) m/s 2

(b)

What is the angular speed of the wheels (in rad/s) when the bicyclist reaches 11.6 m/s? rad/s

(c)

How many radians have the wheels turned through in that time? rad

(d)

How far (in m) has the bicycle traveled? m

–/4 points

13.

SerCPAP11 7.P.007.OP.

My Notes

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Starting from rest, a bicyclist pedals a bicycle such that the angular acceleration of the wheels is a constant 1.40 rad/s 2. The bicycle wheels are 33.5 cm in radius. (a)

2

What is the magnitude of the bicycle's linear acceleration (in m/s )? m/s 2

(b)

What is the angular speed of the wheels (in rad/s) when the linear speed of the bicyclist reaches 10.8 m/s? rad/s

(c)

How many radians have the wheels turned through in that time? rad

(d)

How far (in m) has the bicycle traveled in that time? m

14.

–/2 points

SerCPAP11 7.P.008.

My Notes

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A bicycle is turned upside down while its owner repairs a flat tire. A friend spins the other wheel and observes that drops of water fly off tangentially. She measures the heights reached by drops moving vertically (see figure below). A drop that breaks loose from the tire on one turn rises vertically 60.0 cm above the tangent point. A drop that breaks loose on the next turn rises 50.0 cm above the tangent point. The radius of the wheel is 0.400 m.

(a) Why does the first drop rise higher than the second drop?

This answer has not been graded yet.

(b) Neglecting air friction and using only the observed heights and the radius of the wheel, find the wheel's angular acceleration (assuming it to be constant). (Indicate the direction with the sign of your answer. Take the clockwise direction to be positive.) rad/s2

15.

–/4 points

SerCPAP11 7.P.009.

My Notes

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The diameters of the main rotor and tail rotor of a single-engine helicopter are 7.53 m and 1.00 m, respectively. The respective rotational speeds are 443 rev/min and 4,130 rev/min. Calculate the speeds of the tips of both rotors. main rotor

m/s

tail rotor

m/s

Compare these speeds with the speed of sound, 343 m/s. v main rotor =

v sound

v tail rotor

v sound

=

16.

SerCPAP11 7.P.010.

–/1 points

My Notes

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The tub of a washer goes into its spin-dry cycle, starting from rest and reaching an angular speed of 5.0 rev/s in 9.0 s. At this point, the person doing the laundry opens the lid, and a safety switch turns off the washer. The tub slows to rest in 11.0 s. Through how many revolutions does the tub turn during this 20 s interval? Assume constant angular acceleration while it is starting and stopping.

rev

17.

SerCPAP11 7.P.010.OP.

–/1 points

My Notes

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A top-loading washing machine has a cylindrical basket that rotates about a vertical axis. The basket of one such machine starts from rest and reaches an angular speed of 7.0 rev/s in 7.0 s. The lid of the machine is then opened, which turns off the machine, and the basket slows to rest in 11.0 s. Through how many revolutions does the basket turn during this 18 s interval? Assume constant angular acceleration while it is starting and stopping.

rev

18.

SerCPAP11 7.P.011.

–/2 points

My Notes

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2 after its brakes are A car initially traveling at 26.7 m/s undergoes a constant negative acceleration of magnitude 1.90 m/s

applied. (a) How many revolutions does each tire make before the car comes to a stop, assuming the car does not skid and the tires have radii of 0.325 m? rev (b) What is the angular speed of the wheels when the car has traveled half the total distance? rad/s

19.

SerCPAP11 7.P.012.

–/4 points

My Notes

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A 41.0-cm diameter disk rotates with a constant angular acceleration of 3.00 rad/s2 . It starts from rest at t = 0, and a line drawn from the center of the disk to a point P on the rim of the disk makes an angle of 57.3° with the positive x-axis at this time. (a) At t = 2.44 s, find the angular speed of the wheel. rad/s (b) At t = 2.44 s, find the magnitude of the linear velocity and tangential acceleration of P. linear velocity

m/s

tangential acceleration

m/s2

(c) At t = 2.44 s, find the position of P (in degrees, with respect to the positive x-axis). ° counterclockwise from the +x-axis

20.

–/1 points

SerCPAP11 7.P.013.MI.

My Notes

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A rotating wheel requires 7.00 s to rotate 25.0 revolutions. Its angular velocity at the end of the 7.00-s interval is 97.0 rad/s. What is the constant angular acceleration (in rad/s) of the wheel? rad/s2

21.

–/11 points

SerCPAP11 7.P.013.MI.SA.

My Notes

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This question has several parts that must be completed sequentially. If you skip a part of the question, you will not receive any points for the skipped part, and you will not be able to come back to the skipped part. Tutorial Exercise A rotating wheel requires 11.0 s to rotate 46.0 revolutions. Its angular velocity at the end of the 11.0-s interval is 93.0 rad/s. What is the constant angular acceleration (in rad/s) of the wheel?

22.

SerCPAP11 7.P.014.

–/2 points

An electric motor rotating a workshop grinding wheel at a rate of 1.26

My Notes

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102 rev/min is switched off. Assume the wheel has a

constant negative angular acceleration of magnitude 2.30 rad/s2 . (a) How long does it take for the grinding wheel to stop? s (b) Through how many radians has the wheel turned during the interval found in (a)? rad

23.

SerCPAP11 7.P.015.

–/3 points

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A car initially traveling eastward turns north by traveling in a circular path at uniform speed as shown in the figure below. The length of the arc ABC is 214 m, and the car completes the turn in 35.0 s.

(a) Determine the car's speed. m/s (b) What is the magnitude and direction of the acceleration when the car is at point B? magnitude

m/s2

direction

° counterclockwise from the +x-axis

–/3 points

24.

SerCPAP11 7.P.015.OP.

My Notes

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The figure below shows an object initially at point A traveling in the +x-direction. It turns in a circular path at constant speed until it is traveling in the +y-direction at point C. The quarter-circle arc from A to C is 251 m in length, and the particle moves from A to C in 41.0 s. Point B on the path is 35.0° below the x-axis.

(a)

What is the speed of the object (in m/s)? m/s

(b)

25.

What is the magnitude and direction of the acceleration when the object is at point B? (Enter the magnitude in m/s 2 and the direction in degrees counterclockwise from the +x-axis.) magnitude

m/s2

direction

° counterclockwise from the +x-axis

–/1 points

SerCPAP11 7.P.016.

My Notes

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It has been suggested that rotating cylinders about 10.5 mi long and 3.64 mi in diameter be placed in space and used as colonies. What angular speed must such a cylinder have so that the centripetal acceleration at its surface equals the free-fall acceleration on Earth? rad/s

26.

–/6 points

SerCPAP11 7.P.017.

My Notes

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(a) What is the magnitude of the tangential acceleration of a bug on the rim of an 11.0-in.-diameter disk if the disk accelerates uniformly from rest to an angular speed of 75.0 rev/min in 3.40 s? m/s2 (b) When the disk is at its final speed, what is the magnitude of the tangential velocity of the bug? m/s (c) One second after the bug starts from rest, what is the magnitude of its tangential acceleration? m/s2 (d) One second after the bug starts from rest, what is the magnitude of its centripetal acceleration? m/s2 (e) One second after the bug starts from rest, what is its total acceleration? (Take the positive direction to be in the direction of motion.) magnitude

m/s2

direction

° from the radially inward direction

27.

–/1 points

SerCPAP11 7.P.018.

My Notes

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An adventurous archeologist (m = 87.5 kg) tries to cross a river by swinging from a vine. The vine is 11.0 m long, and his speed at the bottom of the swing is 8.25 m/s. The archeologist doesn't know that the vine has a breaking strength of 1,000 N. Does he make it safely across the river without falling in? es o

28.

–/1 points

SerCPAP11 7.P.018.OP.

My Notes

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An online video daredevil is filming a scene where he swings across a river on a vine. The safety crew must use a vine with enough strength so that it doesn't break while swinging. The daredevil's mass is 84.0 kg, the vine is 11.5 m long, and the speed of the daredevil at the bottom of the swing has been determined to be 8.60 m/s. What is the minimum tension force (in N) the vine must be able to support without breaking?

N

29.

SerCPAP11 7.P.019.

–/7 points

My Notes

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One end of a cord is fixed and a small 0.400-kg object is attached to the other end, where it swings in a section of a vertical circle of radius 1.50 m, as shown in the figure below. When θ = 24.0°, the speed of the object is 5.50 m/s.

(a) At this instant, find the magnitude of the tension in the string. N (b) At this instant, find the tangential and radial components of acceleration. 2

at =

m/s inward

a c=

m/s 2 downward tangent to the circle

(c) At this instant, find the total acceleration. inward and below the cord at

°

(d) Is your answer changed if the object is swinging down toward its lowest point instead of swinging up? es o

(e) Explain your answer to part (d).

This answer has not been graded yet.

SerCPAP11 7.P.020.

–/2 points

30.

My Notes

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Human centrifuges are used to train military pilots and astronauts in preparation for high-g maneuvers. A trained, fit person wearing a g-suit can withstand accelerations up to about 9g (88.2 m/s 2) without losing consciousness.

(a)

If a human centrifuge has a radius of 3.91 m, what angular speed (in rad/s) results in a centripetal acceleration of 9g? rad/s

(b)

What linear speed (in m/s) would a person in the centrifuge have at this acceleration? m/s

31.

SerCPAP11 7.P.021.

–/2 points

My Notes

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A 59.0-kg ice skater is moving at 4.07 m/s when she grabs the loose end of a rope, the opposite end of which is tied to a pole. She then moves in a circle of radius 0.860 m around the pole. (a) Determine the magnitude of the force exerted by the horizontal rope on her arms. kN (b) Compare this force with her weight. Frope = W

32.

SerCPAP11 7.P.022.MI.

–/2 points

My Notes

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A 37.0-kg child swings in a swing supported by two chains, each 2.98 m long. The tension in each chain at the lowest point is 434 N. (a) Find the child's speed at the lowest point. m/s (b) Find the force exerted by the seat on the child at the lowest point. (Ignore the mass of the seat.) N (upward)

33.

–/10 points

SerCPAP11 7.P.022.MI.SA.

My Notes

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This question has several parts that must be completed sequentially. If you skip a part of the question, you will not receive any points for the skipped part, and you will not be able to come back to the skipped part. Tutorial Exercise A 37.5-kg child swings in a swing supported by two chains, each 2.97 m long. The tension in each chain at the lowest point is 421 N. (a) Find the child's speed at the lowes...