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bogdanovich [222]

2 years ago

12

Allison kicks soccer ball so that it has an initial velocity 19 m/s at an angle of 21° above the ground. How much time does it t

ake for the soccer ball to reach its maximum height

1 answer:

Serga [27]2 years ago

6 0

The answer is B.
t = Vy / g
t =( 19 x sin21 ) / 9.8 = 0.69s

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Two stones are launched from the top of a tall building. One stoneis thrown in a direction 30.0^\circ above the horizontal with

Butoxors [25]

Answer:

Part A)

t(1) > t(2), the stone thrown 30 above the horizontal spends more time in the air.

Part B)

x(f1) > x(f2), the first stone will land farther away from the building.

Explanation:

<u>Part A)</u>

Let's use the parabolic motion equation to solve it. Let's define the variables:

y(i) is the initial height, it is a constant.
y(f) is the final height, in our case is 0
v(i) is the initial velocity (v(i)=16 m/s)
θ1 is the first angle, 30°
θ2 is the first angle, -30°

For the first stone

$y_{f1}=y_{i1}+v*sin(\theta_{1})t_{1}-0.5gt_{1}^{2}$

$0=y_{i1}+16*sin(30)t_{1}-0.5*9.81*t_{1}^{2}$

$0=y_{i1}+8t_{1}-4.905*t_{1}^{2}$ (1)

For the second stone

$0=y_{i2}+16*sin(-30)t_{2}-4.905t_{2}^{2}$

$0=y_{i2}-8t_{2}-4.905t_{2}^{2}$ (2)

If we solve the equation (1) we will have:

$t_{1}=\frac{-8\pm \sqrt{64+19.62*y_{i}}}{-9.81}$

We can do the same procedure for the equation (2)

$t_{1}=\frac{8\pm \sqrt{64+19.62*y_{i}}}{-9.81}$

We can analyze each solution to see which one spends more time in the air.

It is easy to see that the value inside the square root of each equation is always greater than 8, assuming that the height of the building is > 0. Now, to get positive values of t(1) and t(2) we need to take the negative option of the square root.

Therefore, t(1) > t(2), it means that the stone thrown 30 above the horizontal spends more time in the air.

<u>Part B)</u>

We can use the equation of the horizontal position here.

<u>First stone</u>

$x_{f1}=x_{i1}+vcos(30)t_{1}$

$x_{f1}=0+13.86*t_{1}$

$x_{f1}=13.86*t_{1}$

<u>Second stone</u>

$x_{2}=x_{i2}+vcos(-30)t_{2}$

$x_{1}=0+13.86*t_{1}$

$x_{1}=13.86*t_{2}$

Knowing that t(1) > t(2) then x(f1) > x(f2)

Therefore, the first stone will land farther away from the building.

They land at different points at different times.

I hope it helps you!

3 0

3 years ago

How to make a paper airplane curve down and fly upside down?

Ainat [17]

Throw it sideways and try to make it spin around but it needs to be thrown high up then it should kinda glide down

8 0

2 years ago

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One block rests upon a horizontal surface. A second identical block rests upon the first one. The coefficient of static friction

Sophie [7]

Answer:

F = 156.3 N

Explanation:

Let's start with the top block, apply Newton's second law

F - fr = 0

F = fr

fr = 52.1 N

Now we can work with the bottom block

In this case we have two friction forces, one between the two blocks and the other between the block and the surface. In the exercise, indicate that the two friction coefficients are equal

we apply Newton's second law

Y axis

N - W₁ -W₂ = 0

N = W₁ + W₂

as the two blocks are identical

N = 2W

X axis

F - fr₁ - fr₂ = 0

F = fr₁ + fr₂

indicates that the lower block is moving below block 1, therefore the upper friction force is

fr₁ = 52.1 N

fr₁ = μ N

a

s the normal in the lower block of twice the friction force is

fr₂ = μ 2N

fr₂ = 2 μ N

fr₂ = 2 fr₁

we substitute

F = fr₁ + 2 fr₁

F = 3 fr₁

F = 3 52.1

F = 156.3 N

7 0

2 years ago

A ball is thrown into the air with an upward velocity of 20 feet per second. Its height, h, in feet after t seconds is given by

Margarita [4]

Thank you for posting your question here at brainly. Feel free to ask more questions.
<span>The best and most correct answer among the choices provided by the question is B. Reaches a max height of 8.25 feet after 0.63 seconds</span> . <span><span>

</span><span>Hope my answer would be a great help for you. </span> </span>

<span> </span>

3 0

3 years ago

A 755 N force is used to push a 15 Kg box across the floor. What is the acceleration of the box?

cluponka [151]

Answer:

good question!

Explanation:

3 0

2 years ago

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