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Ch 03: Motion in Two or Three Dimensions

Chapter 3, Problem 3

A rookie quarterback throws a football with an initial upward velocity component of 12.0 m/s and a horizontal velocity component of 20.0 m/s. Ignore air resistance. (b) How high is this point?

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Welcome back everybody. We are told that a soft ball is thrown with an initial horizontal velocity of 15 m/s. And we are also told that it's vertical Initial velocity is equal to that. So the Y component is also m/s. That means we are looking at a velocity vector, an initial velocity vector of something like this. Now this softball is going to follow projectile motion means it's going to follow an arc that's parabolic kind of like that. And at some point up here it is going to reach its maximum and we need to figure out the distance from the ground designated by Y max at that maximum point. Well, our why max here is going to be equal to one half times our acceleration due to gravity times our time. We know this, that's just an equation were given because we're dealing with projectile motion. But what is our time Here? Well, our time here is our time it takes to reach that maximum height. Now this is given by another equation which is equal to our initial vertical velocity over our acceleration due to gravity. So now that we have these equations, let's go ahead and plug some values in our T max is equal to our initial vertical velocity of 15 divided by our acceleration due to gravity. And this is going to give us 1.53 seconds to reach its maximum height. Now let's go ahead and plug that into our maximum height formula. We have one half times the acceleration due to gravity, times our time that we just found squared. And when you plug this into your calculator, we get 11.48 m corresponding to our answer choice of a thank you guys so much for watching. Hope this video helped, and we will see you all in the next one.
Related Practice
Textbook Question
A shot putter releases the shot some distance above the level ground with a velocity of 12.0 m/s, 51.0° above the horizontal. The shot hits the ground 2.08 s later. Ignore air resistance. (c) How far did she throw the shot horizontally?
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Textbook Question
In a carnival booth, you can win a stuffed giraffe if you toss a quarter into a small dish. The dish is on a shelf above the point where the quarter leaves your hand and is a horizontal distance of 2.1 m from this point (Fig. E3.19). If you toss the coin with a velocity of 6.4 m/s at an angle of 60° above the horizontal, the coin will land in the dish. Ignore air resistance. (a) What is the height of the shelf above the point where the quarter leaves your hand?

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Textbook Question
In a carnival booth, you can win a stuffed giraffe if you toss a quarter into a small dish. The dish is on a shelf above the point where the quarter leaves your hand and is a horizontal distance of 2.1 m from this point (Fig. E3.19). If you toss the coin with a velocity of 6.4 m/s at an angle of 60° above the horizontal, the coin will land in the dish. Ignore air resistance. (b) What is the vertical component of the velocity of the quarter just before it lands in the dish?

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Textbook Question
A rookie quarterback throws a football with an initial upward velocity component of 12.0 m/s and a horizontal velocity component of 20.0 m/s. Ignore air resistance. (c) How much time (after it is thrown) is required for the football to return to its original level? How does this compare with the time calculated in part (a)?
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Textbook Question
A rookie quarterback throws a football with an initial upward velocity component of 12.0 m/s and a horizontal velocity component of 20.0 m/s. Ignore air resistance. (d) How far has the football traveled horizontally during this time?
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Textbook Question
The froghopper, Philaenus spumarius, holds the world record for insect jumps. When leaping at an angle of 58.0° above the horizontal, some of the tiny critters have reached a maximum height of 58.7 cm above the level ground. (See Nature, Vol. 424, July 31, 2003, p. 509.) (a) What was the takeoff speed for such a leap?
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