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clairez93
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Homework Statement
1. A carnival Ferris wheel has a 15-m radius and completes five turns about its horizontal axis every minute. What is the acceleration of a passenger at his lowest point during the ride?
a) 5.7 m/s^2 downward
b) 4.1 m/s^2 upward
c) 14 m/s^2 downward
d) 4.1 m/s^2 downward
e) 19 m/s^2 downward
Answer: A
2. A car travels in a due northerly direction at a speed of 55 km/h. The traces of rain on the die windows of the car make an angle of 60 degrees with respect to the horizontal. If the rain is falling vertically with respect to the earth, what is the speed of the rain with respect to the earth?
a) 48 km/h
b) 95 km/h
c) 58 km/h
d) 32 km/h
e) 80 km/h
Answer: B
3. Two identical balls are at rest and side by side at the top of a hill. You let one ball, A, start rolling down the hill. A little later you start the second ball, B, down the hill by giving it a shove. The second ball rolls down the hill along a line parallel to the path of the first ball and passes it. At the instant ball B passes ball A:
a) it has the same position and the same velocity as A
b) it has the same position and the same acceleration as A
c) it has the same velocity and the same acceleration as A
d) it has the same displacement and the same velocity as A
e) it has the same displacement and the same acceleration as A
Answer: E
4. A toy rocket, launched from ground, rises vertically with an acceleration of 20 m/s^2 for 6.0 s until its motor stops. Disregarding any air resistance, what maximum height above the ground will the rocket achieve?
a) 1.1 km
b) 0.73 km
c) 1.9 km
d) 0.39 km
e) 1.5 km
Answer: A
5. A ball is thrown vertically upward with an initial speed of 20 m/s. Two seconds later, a stone is thrown vertically (from the same initial height as the ball) with an initial speed of 24 m/s. At what height above the release point will the ball and stone pass each other?
a) 17 m
b) 21 m
c) 18 m
d) 27 m
e) 31 m
Answer: A
Homework Equations
The Attempt at a Solution
1. [tex]\frac{5 rev}{1 min} = \frac{5(2\pi*15)}{60} = 7.85 m/s[/tex]
[tex]a = \frac{v^{2}}{r} = \frac{7.85^{2}}{15} = 4.11 m/s^{2}[/tex]
Answer says 5.7 m/s^2 though.
2. Not sure how to approach this one at all.
3. Why do the two balls have the same acceleration? If one can pass the other, at a later time, then shouldn't it accelerate faster?
4. [tex]V_{f} = V_{i} + at[/tex]
[tex]0 = V_{i} + (20)(6)[/tex]
[tex]V_{i} = -120[/tex]
[tex]y = \frac{1}{2}at^{2} + V_{i}t[/tex]
[tex]= \frac{1}{2}(20)(6)^{2} - 120(6) = -360[/tex]
No answer choices available...
5. [tex]y_{b} = \frac{1}{2}(-9.8)t^{2} + 20t[/tex]
[tex]y_{b}(2) = \frac{1}{2}(-9.8)(2)^{2} + 20(2) = 20.4[/tex]
[tex]y_{b} = \frac{1}{2}(-9.8)t^{2} + 20t + 20.4[/tex]
[tex]y_{s} = \frac{1}{2}(-9.8)t^{2} + 24t[/tex]
[tex]\frac{1}{2}(-9.8)t^{2} + 20t + 20.4 = \frac{1}{2}(-9.8)t^{2} + 24t[/tex]
[tex]4t = 20.4[/tex]
[tex]t = 5.1[/tex]
[tex]y = \frac{1}{2}(-9.8)(5.1)^{2} + 24(5.1) = -5.049 m[/tex]
Again, no answer choices there for that...
Any help appreciated, thanks! :]