Transcript The vector r indicates the instantaneous displacement of a

The vector r indicates the instantaneous displacement of a
projectile from the origin. At the instant when the projectile is at r, its
velocity and acceleration vectors are v and a. Which statement is
correct? Select the correct answer.
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a is always perpendicular to vx
a is always perpendicular to vy
a is always perpendicular to v
a is always perpendicular to r
v is always perpendicular to r
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The speed of a particle moving in a circle 7.5m in radius increases
at the constant rate of 5.0 m/s2. At an instant when the magnitude
of the total acceleration is 8.4 m/s2 what is the speed of the
particle? Select the correct answer.
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7.1 m/s
8.6 m/s
5.0 m/s
7.9 m/s
6.1 m/s
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A ball is thrown horizontally from the top of a building 0.11 km
high. The ball strikes the ground at a point 65m horizontally away
from and below the point of release. What is the speed of the ball
just before it strikes the ground? Select the correct answer.
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48 m/s
46 m/s
14 m/s
60 m/s
33 m/s
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A baseball is hit at ground level. The ball is observed to reach its
maximum height above ground level 4.6s after being hit. And 3.1s
after reaching this maximum height, the ball is observed to barely
clear a fence that is 68.0m from where it was hit. How high is the
fence? Select the correct answer.
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56.6 m
78.6 m
2.2 m
24.3 m
13.2 m
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A rock is projected from the edge of the top of a building with an initial
velocity of 16.6m/s at an angle of 53°, above the horizontal. The rock
strikes the ground a horizontal distance of 56.4m from the base of the
building. Assume that the ground is level and that the side of the building is
vertical. How tall is the building? Select the correct answer.
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81.3 m
62.5 m
90.3 m
46.2 m
99.3 m
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A student in the front of a school bus tosses a ball to another
student in the back of the bus while the bus is moving forward at
constant velocity. The speed of the ball as seen by a stationary
observer in the street _____ . Select the correct answer.
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may be either greater, smaller, or
equal to that observed inside the
bus
is the same as that observed
inside the bus
may be either greater or smaller
than that observed inside the bus
is less than that observed inside
the bus
is greater than that observed
inside the bus
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A race car moving with a constant speed of 72m/s
completes one lap around a circular track in 62s. What
is the magnitude of the acceleration of the race car?
Select the correct answer.
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7.3 m/s2
1.2 m/s2
2.3 m/s2
5.4 m/s2
9.1 m/s2
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A 0.22-km wide river has a uniform flow speed of 5.5 m/s toward
the east. A boat with a speed of 9.6 m/s relative to the water leaves
the south bank and heads in such a way that it crosses to a point
directly north of its departure point. How long does it take the boat
to cross the river? Select the correct answer.
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28 s
23 s
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15 s
54 s
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At the lowest point in a vertical dive (radius = 0.69 km), an airplane
has a speed of 380 km/h which is not changing. Determine the
magnitude of the acceleration of the pilot at this lowest point.
Select the correct answer.
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16 m/s2
21 m/s2
2.6 m/s2
28 m/s2
6.5 m/s2
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A particle starts from the origin at t = 0 with a velocity of (13i -10j)
m/s and moves in the xy plane with a constant acceleration of a =
(5.2i - 8.2j)m/s2 What is the speed of the particle at t = 3.8s?
Select the correct answer.
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53 m/s
39 m/s
74 m/s
23 m/s
59 m/s
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A particle moves in the xy plane with a constant acceleration
given by a = -1.8j m/s2. At t = 0. its position and velocity are
40i m and (-8.7i + 2.8j) m/s. respectively. What is the
distance from the origin to the particle at t = 8.6s? Select
the correct answer.
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55 m
86 m
42 m
35 m
46 m
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A projectile is thrown from the top of a building with an initial
velocity of 11 m/s in the horizontal direction. If the top of the
building is 10 m above the ground, how fast will the projectile be
moving just before it strikes the ground? Select the correct
answer.
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18 m/s
25 m/s
14 m/s
16 m/s
15 m/s
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An airplane flies horizontally with a speed of 300 m/s at an altitude
of 390 m. Assume that the ground is level. At what horizontal
distance from a target must the pilot release a bomb so as to hit the
target? Select the correct answer.
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2.7 km
3.8 km
3.1 km
1.2 km
1.9 km
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