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2 years ago

A ball is thrown horizontally from the top of

Physics

1 answer:

nordsb [41]2 years ago

7 0

Answer:

54.0 m/s

Explanation:

We can start by calculating the time it takes for the ball to reach the ground. This can be done by using the equation for the vertical position of the ball at time t:

$y(t) = h + u_y t - \frac{1}{2}gt^2$

where

h = 140 m is the initial height

$u_y =0$ is the initial vertical velocity (the ball is thrown horizontally)

g = 9.8 m/s^2 is the acceleration of gravity

When the ball reaches the ground, y=0, so we solve for t to find the time of flight:

$0=h-\frac{1}{2}gt^2\\t=\sqrt{\frac{2h}{g}}=\sqrt{\frac{2(140)}{9.8}}=5.35 s$

We can find the vertical speed of the ball at the moment of the impact by using

$v_y=u_y+gt$

Using t = 5.35 s,

$v_y=0+(9.8)(5.35)=52.4 m/s$

The motion of the ball along the horizontal direction is a uniform motion - so the horizontal velocity is constant during the whole motion, and it is given by

$v_x = \frac{d}{t}$

where

d = 69 m

is the distance travelled horizontally. Using t = 5.35 s,

$v_x = \frac{69}{5.35}=12.9 m/s$

And therefore, the speed of the ball at the moment of the impact is given by

$v=\sqrt{v_x^2+v_y^2}=\sqrt{(12.9)^2+(52.4)^2}=54.0 m/s$

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Ivanshal [37]

Answer:

Resonance depends on objects, this may happen for example when you play guitar in a given room, you may find that for some notes the walls or some object vibrate more than for others. This is because those notes are near the frequency of resonance of the walls.

So waves involved are waves that can move or affect objects (in this case the pressure waves of the sound, and the waves that are moving the wall).

this means that the waves are mechanic waves.

Now, in electromagnetics, you also can find resonance frequencies for electromagnetic waves trapped in things called cavities, but this is a different topic.

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3 years ago

Can you have zero displacement and nonzero average velocity? Zero displacement and nonzero velocity? Illustrate your answers on

Svetlanka [38]

a) Not possible

b) Yes, it's possible (see graph in attachment)

Explanation:

The average velocity of a body is defined as the ratio between the displacement and the time elapsed:

$v=\frac{\Delta x}{\Delta t}$

where

$\Delta x$ is the displacement

$\Delta t$ is the time elapsed

In this problem, we want to have zero displacement and non-zero average velocity. From the equation above, we see that this is not possible. In fact, if the total displacement is zero,

$\Delta x = 0$

And therefore as a consequence,

$v=0$

which means that the average velocity is zero.

Here we want to have zero displacement and non-zero velocity. In this case, it is possible: in fact, we are not talking about average velocity, but we are talking about (instantaneous) velocity.

On a position-time graph, the instantaneous velocity is the slope of the graph. Look at the graph in attachment. We see that the position of the object first increases towards positive value, then it decreases (the object starts moving backward), then becomes negative, then it increases again until returning to the original position, x = 0.

In all of this, we notice that the total displacement of the object is zero:

$\Delta x = 0$

However, we notice that the instantaneous velocity of the object at the various instants is not zero, because the slope of the graph is not zero.

Learn more about average velocity:

brainly.com/question/8893949

brainly.com/question/5063905

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