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2 years ago

A tennis player tosses a tennis ball straight up and then catches it after 1.77 s at the same height as the point of release.

Physics

1 answer:

Alex_Xolod [135]2 years ago

3 0

(a) The acceleration of the ball while it is in flight has a magnitude of 9.81 m/s2 in downward direction.

(b) The velocity of the ball when it reaches its maximum height is zero.

(d) The maximum height it reaches is 15.36 m.

<h3>Acceleration of the ball</h3>

The acceleration of the ball while it is in flight has a magnitude of 9.81 m/s2 in downward direction.

<h3>Velocity of the ball at maximum height</h3>

The velocity of the ball decreases as the ball moves upwards and eventually becomes zero at maximum height.

<h3>Initial velocity of the ball</h3>

v = u - gt

at maximum height, final velocity, v = 0

0 = u - gt

u = gt

u = 9.81 x 1.77

u = 17.36 m/s

<h3>Maximum height reached by the projectile</h3>

h = ut - ¹/₂gt

h = 17.36(1.77) - ¹/₂(9.81)(1.77²)

h = 15.36 m

Thus, the acceleration of the ball while it is in flight has a magnitude of 9.81 m/s2 in downward direction.

The velocity of the ball when it reaches its maximum height is zero.

The initial velocity of the ball is 17.36 m/s.

The maximum height it reaches is 15.36 m.

Learn more about maximum height here: brainly.com/question/12446886

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The speedometer on your car reads 35 mph. What is this measuring? A. average speed B. instantaneous speed C. velocity D. acceler

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B. instantaneous speed

The speedometer of a car show instantaneous speed.
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If the mass of each object is the same, 18 g, which object will have the largest density? *

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3 years ago

A penny is kicked horizontally off the roof of a 10-story building (33.3 m high) and lands 52 m away on the ground. A) what is t

yanalaym [24]

A) The penny was kicked horizontally off the building. By this very statement, the penny had 0 initial vertical velocity.

B) Apply the following kinematics equation to the penny's vertical motion:

D = Vt + 0.5At²

D = vertical distance traveled, t = time, V = initial vertical velocity, A = vertical acceleration

Given values:

D = 33.3m, V = 0m/s, A = 9.81m/s²

Plug in and solve for t:

33.3 = 4.905t²

t = 2.61s

C) The penny fell for 2.61 seconds, therefore it moved horizontally for 2.61 seconds.

v = x/t

v = horizontal velocity, x = horizontal distance traveled, t = time

Given values:

x = 52m, t = 2.61s

Plug in and solve for v:

v = 52/2.61

v = 19.9m/s

D) Let's calculate the penny's vertical speed right before it hits the ground:

v = at

v = final vertical speed, a = vertical acceleration, t = time

Given values:

a = 9.81m/s², t = 2.61s

Plug in and solve for v:

v = 9.81(2.61)

v = 25.6m/s

Use the Pythagorean theorem to find the final speed:

V = √(Vx²+Vy²)

V = final speed, Vx = final horizontal speed, Vy = final vertical speed

Given values:

Vx = 19.9m/s, Vy = 25.6m/s

Plug in and solve for V:

V = √(19.9²+25.6²)

V = 32.4m/s

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3 years ago

g initial angular velocity of 39.1 rad/s. It starts to slow down uniformly and comes to rest, making 76.8 revolutions during the

MrRa [10]

Answer:

Approximately $-1.58\; \rm rad \cdot s^{-2}$ .

Explanation:

This question suggests that the rotation of this object slows down "uniformly". Therefore, the angular acceleration of this object should be constant and smaller than zero.

This question does not provide any information about the time required for the rotation of this object to come to a stop. In linear motions with a constant acceleration, there's an SUVAT equation that does not involve time:

$v^2 - u^2 = 2\, a\, x$ ,

where

$v$ is the final velocity of the moving object,
$u$ is the initial velocity of the moving object,
$a$ is the (linear) acceleration of the moving object, and
$x$ is the (linear) displacement of the object while its velocity changed from $u$ to $v$ .

The angular analogue of that equation will be:

$(\omega(\text{final}))^2 - (\omega(\text{initial}))^2 = 2\, \alpha\, \theta$ , where

$\omega(\text{final})$ and $\omega(\text{initial})$ are the initial and final angular velocity of the rotating object,
$\alpha$ is the angular acceleration of the moving object, and
$\theta$ is the angular displacement of the object while its angular velocity changed from $\omega(\text{initial})$ to $\omega(\text{final})$ .

For this object:

$\omega(\text{final}) = 0\; \rm rad\cdot s^{-1}$ , whereas
$\omega(\text{initial}) = 39.1\; \rm rad\cdot s^{-1}$ .

The question is asking for an angular acceleration with the unit $\rm rad \cdot s^{-1}$ . However, the angular displacement from the question is described with the number of revolutions. Convert that to radians:

$\begin{aligned}\theta &= 76.8\; \rm \text{revolution} \\ &= 76.8\;\text{revolution} \times 2\pi\; \rm rad \cdot \text{revolution}^{-1} \\ &= 153.6\pi\; \rm rad\end{aligned}$ .

Rearrange the equation $(\omega(\text{final}))^2 - (\omega(\text{initial}))^2 = 2\, \alpha\, \theta$ and solve for $\alpha$ :

$\begin{aligned}\alpha &= \frac{(\omega(\text{final}))^2 - (\omega(\text{initial}))^2}{2\, \theta} \\ &= \frac{-\left(39.1\; \rm rad \cdot s^{-1}\right)^2}{2\times 153.6\pi\; \rm rad} \approx -1.58\; \rm rad \cdot s^{-1}\end{aligned}$ .

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3 years ago

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natali 33 [55]

Answer:. Option c

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The direction of the velocity is the direction of the electromagnetic wave.

The wave is already moving towards the negative y axis (-j) and the magnetic field is already pointing towards the positive x axis (i)

From cross product of unit vectors

i × j = k

i × k = - j

With the second identity, we can see that the electric field will be pointing towards the positive of the x axis (k).

Option c is validated

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3 years ago