Question 1
Correct
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What is the acceleration of a skydiver at terminal velocity whose mass is 80 kg and cross-sectional area is
... [Show More] 14 m2
. The density of the air he is falling through is 0.9984 g /
m
3
. The drag coe_cient has a value of 0.485.
Select one:
a. 15.2 m / sec2
b. 56.4 m / sec2
c. 0 m / sec2
d. 481 m / sec2
e. None of the above
Question 2
Incorrect
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Calculate x = vt + 1 at2 , where v = 0.227 m/s, t = 11.1s, and a = 9.80 m/s
2
. 2
Select one:
a. 606.2487 m
b. 606 m
c. 605.5 m
d. 606.249 m
Question 3
Correct
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Which of the following statements concerning an object in free fall through the atmosphere is incorrect?
Select one:
a. Air resistance opposes the motion of an object moving through air and exists because a moving object collides with air molecules.
b. The speed of a falling object increases due to the frictional force of air drag.
c. Given two spherical objects made of the same material and dropped from the same height, the one with the larger cross-sectional area will experience
increased air resistance.
d. When the magnitude of the air drag equals that of the object's weight, the net force on the object is zero. The object then falls with a maximum
constant velocity called the terminal velocity.
PHY250_TW | Chapter 3: Dynamics
The correct answer is: 0 m /sec2
The correct answer is: 606 m
The correct answer is: The speed of a falling object increases due to the frictional force of air drag.
Question 5
Correct
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Which of the following is a correct statement concerning the velocity of a particle in uniform circular motion?
Select one:
a. The velocity is in the same direction as the angular velocity.
b. The velocity is directed radially inward.
c. The velocity is in the same direction as the centripetal acceleration.
d. The velocity is constantly changing directions.
Question 6
Incorrect
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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.
Question 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.
The correct answer is: Displacement: 9 blocks
Distance: 15.5 blocks
The correct answer is: The velocity is constantly changing directions.
The correct answer is: All the cross-terms are equal to zero.
The correct answer is: 52 m /s
A woman drives 2 blocks north, stops, continues on for another 4.5 blocks, and then makes a U-turn and drives south 3.25 blocks. After stopping momentarily she
drives 5.75 blocks north. Which of the following is the magnitude of the woman’s displacement and distance traveled?
Select one:
a. Displacement: 15.5 blocks
Distance: 15.5 blocks
b. Displacement: 15.5 blocks
Distance: 9 blocks
c. Displacement: 9 blocks
Distance: 15.5 blocks
d. Displacement: 9 blocks
Distance: 9 blocks
Question 4
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Question 9
Correct
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What is the scalar product of two perpendicular vectors?
Select one:
a. the total of their magnitudes
b. the product of their magnitudes
c. zero
d. the difference of their magnitudes
Question 10
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An airplane has an initial velocity with respect to the ground of 200 mph in an eastward direction. A strong wind begins to blow with a velocity of 80 mph from north tosouth. What are the x-and y-components of the total velocity of the plane when the wind is taken into account? Let north be the positive y-direction and east be the
positive x-direction.
Select one:
a. vx = +200 mph
vy = +80 mph
b. vx = +200 mph
vy = −80 mph
c. vx = +80 mph
vy = +200 mph
d. vx = +215 mph
vy = −80 mph
Question 11
Correct
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Consider a basket with 3.046 kg of fruit. When you weigh the whole package (fruit + basket), the reading on the scale is 4.2 kg. What is the most realistic weight of the basket alone?
Select one:
a. 1.2 kg
b. 1.154 kg
c. 1.15 kg
d. 1 kg
The correct answer is: −35 mph
The correct answer is: zero
The correct answer is: vx = +200 mph
vy = −80 mph. [Show Less]