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2.4 自由落体竖直上抛

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2.4 自由落体 竖直上抛
Class exercise
1) How long does it take for an object to fall 10m?
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2)Calculate the speed of the object when it hits the ground from a height of 100 meters
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3)Test people's reaction times with $100.
4)If an object is thrown vertically upward at a certain initial velocity from a 12m tall tower,
and it takes 2s to reach the ground,
(1) calculate the initial velocity of the object.
(2) What is the maximum height the object can rise to?
(3) How fast does the object hit the ground?
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5)A pitcher tosses a baseball up along a y axis, with an initial speed of 12 m/s.
(a) How long does the ball take to reach its maximum height?
(b) What is the ball’s maximum height above its release point?
(c) How long does the ball take to reach a point 5.0 m above its release point?
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6) In Fig, what is the acceleration at 1.0 s?
A) 0
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B) 2.0 m/s
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C) -2.5 m/s
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D) 10 m/s
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7) In Fig, what is the average acceleration from 0 to 8.0 s?
A) 0
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B) 2.0 m/s
2
C) -2.5 m/s
2
D) 10 m/s
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8) In Fig, what is the displacement from 0 to 8.0 s?
A) 20 m
B) 40 m
C) 60 m
D) 80 m
9) A stone is dropped from the roof of a high building. A second stone is dropped 1.30 s
later. How far apart are the stones when the second one has reached a speed of 12.0 m/s?
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10)A person jumps out a fourth-story window 18.0 m above a firefighter’s safety net. The
survivor stretches the net 1.0 m before coming to rest, What was the average deceleration
experienced by the survivor when she was slowed to rest by the net?
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