by Dustin Glazier, January 1998

A baseball leaves the bat with an upward velocity of 54 m/s.

How high does it go? What time does it take to reach the top?

What total time will it be in the air?
(149 m, 5.5 s, 11s)
Here is what you start with:

- X = ? (we will call the displacement on the y-axis X)
- t = ?
- Vi = 54 m/s
- V
_{a}= ? - V = 0 (it hits the ground)
- a = -9.8 m/s/s This is gravity

We now move on to the time it takes for it to reach the top: I think that X = Vit +

We then plug in the numbers:

149 = 0t +

Therefore the time for the whole flight is t = 11 seconds

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with a velocity of -24 m/s. What time were they in the air?

How high is the cliff? (2.4 s, 29 m) Here is what you start with:

- X = ?
- t = ?
- Vi = 0 m/s
- V
_{a}= ? - V = -24 m/s
- a = -9.8

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the water. (1 m = 3.281 f) What time does it take them to hit the water,

and how fast are they going

when they do hit the water? (4.3 s, 42 m/s) Here is what you start with:

- X = 300 ft or 91.44 m
- t = ?
- Vi = 0 (he started at rest)
- V
_{a}= ? - V = ?
- a = 9.8 m/s/s (he's going down)

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upward velocity and hits the water 1.9 seconds later. What was his initial upward velocity?

To what height above the diving board did he rise before going down?

With what speed did he hit the water? (4.0 m/s, .84 m, -14.6 m/s) Here is what you start with:

- X = 10.0 m
- t = 1.9 seconds
- Vi = ?
- V
_{a}= ? - V = ?
- a = 9.80 m/s/s (The acceleration of free fall on Earth)

Since were solving for Vi lets find one that solves for it.

X = Vit +

10m = Vi(1.9s)+

It's important to remember that the X = 10.84 because that ís the highest point of the arc

Because the original X = 10 m and the distance higher is .84 m Working it through and remembering that it ís negative because he's going down:

V

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If you measure skid marks that are 34 m long, with what speed

was the car going that made them? (25 m/s) Here is what you start with:

- X = 34 m
- t = ?
- Vi = ?
- V
_{a}= ? - V = 0 m/s (the car is stopped)
- a = -9.4 m/s/s

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distance can it attain a speed of 25 m/s starting from rest?

(2083 m) Here is what you start with:

- X = ?
- t = ?
- Vi = 0 (it tells us that it starts from rest)
- V
_{a}= ? - V = 25 m/s
- a = .15 m/s/s

Linda, something from the meat cabinet. Or perhaps the number cabinet. 25

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a distance of 120 m. What is its acceleration? Over what distance

can it reach a speed of 85 m/s? (11.7 m/s/s, 309 m) Here is what you start with:

- X = 120 m
- t = ?
- Vi = 0 m/s
- V
_{a}= ? - V = 53 m/s
- a = ?

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and can accelerate at 4.7 m/s/s. What is the minimum length of runway? (681 m) Here is what you start with:

- X = ?
- t = ?
- Vi = 0 (from rest)
- V
_{a}= ? - V = 80 m/s
- a = 4.7 m/s/s

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1000 m above the ground just as it hits the ground? (-140 m/s) Here is what you start with:

- X = 1000 m
- t = ?
- Vi = 0 m/s
- V
_{a}= ? - V = ?
- a = 9.8 m/s/s

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What is the acceleration of the bullet while it is in the barrel? (135,000 m/s/s) Here is what you start with:

- X = .75 m
- t = ?
- Vi = 0 m/s
- V
_{a}= ? - V = 450 m/s
- a = ?

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Hey this page was not easy, but I feel privileged to have been able to help you grasp

Physics. And I really needed the extra credit! Happy Solving!!