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3 years ago

15

A ball is dropped from rest at height of 20m. If it loses 25% of its kinetic energy when it strikes the ground. What is the heig

ht to which it bounces?

1 answer:

victus00 [196]3 years ago

6 0

Answer:

15 meters

Explanation:

The inicial energy of the ball is just potencial energy, and its value is:

E = m * g * h = m * g * 20,

where m is the ball mass, and g is the value of gravity.

In the moment that the ball strickes the ground, all potencial energy transformed into kinetic energy, and 25% of this energy is lost, so the total energy at this moment will be:

E' = 0.75 * E = 0.75 * m * g * 20 = 15*m*g

This kinetic energy will make the ball goes up again, and at the maximum height, all kinetic energy is transformed back into potencial energy.

So, as the mass and the gravity are constants, we can calculate the height the ball will reach:

E' = m*g*h = 15*m*g -> h = 15 meters

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In concave mirror, the size of image depends upon

irina1246 [14]

Answer:

The distance of the object placed on the principal axis from the concave mirror.

Explanation:

In a concave mirror, the nature of the image formed formed by the object placed in front of the mirror depends on the position of the object placed in from of the mirror. It all depends on the distance between the mirror and the object placed on the principal axis.

The closer the object is to the lens, the more larger or magnified the image formed will be. For example an object placed between the focal point and the pole of a concave produces a much larger image than an object placed beyond the centre of curvature of such mirror.

8 0

3 years ago

Read 2 more answers

Un satélite geoestacionario se encuentra a una distancia de 120.000 km sobre la superficie de Júpiter. Determine: a. El periodo

Lisa [10]

Answer:

a) a geostationary satellite is that it is always at the same point with respect to the planet,

b) f = 2.7777 10⁻⁵ Hz

c) d) w = 1.745 10⁻⁴ rad / s

Explanation:

a) The definition of a geostationary satellite is that it is always at the same point with respect to the planet, that is, its period of revolutions is the same as the period of the planet

T = 10 h (3600 s / 1h) = 3.6 104 s

b) the period the frequency are related

T = 1 / f

f = 1 / T

f = 1 / 3.6 104

f = 2.7777 10⁻⁵ Hz

c) the distance traveled by the satellite in 1 day

The distance traveled is equal to the length of the circumference

d = 2pi (R + r)

d = 2pi (69 911 103 + 120 106)

d = 1193.24 m

d) the angular velocity is the angle traveled between the time used.

.w = 2pi /t

w = 2pi / 3.6 10⁴

w = 1.745 10⁻⁴ rad / s

how fast is

v = w r

v = 1.75 10-4 (69.911 106 + 120 106)

v = 190017 m / s

5 0

3 years ago

A soccer player applies a force of 48.4 N to a soccer ball while kicking it. If the ball has

AlekseyPX

Answer:

C. 110 m/s2

Explanation:

Force = Mass x Acceleration

Since we have the force and the mass, we can rearrange this equation to solve for acceleration by dividing both sides by mass:

Force/Mass = (Mass x Acceleration)/Mass

Acceleration = Force/Mass

Now we just have to plug in our values and calculate!

Acceleration = 48.4/0.44

Acceleration = 110m/s/s

It is option C. 110 m/s2

Hope this helped!

6 0

3 years ago

Read 2 more answers

uniform disk with mass 40.0 kg and radius 0.200 m is pivoted at its center about a horizontal, frictionless axle that is station

Alex787 [66]

Answer:

The magnitude of the tangential velocity is $v= 0.868 m/s$

The magnitude of the resultant acceleration at that point is $a = 4.057 m/s^2$

Explanation:

From the question we are told that

The mass of the uniform disk is $m_d = 40.0kg$

The radius of the uniform disk is $R_d = 0.200m$

The force applied on the disk is $F_d = 30.0N$

Generally the angular speed i mathematically represented as

$w = \sqrt{2 \alpha \theta}$

Where $\theta$ is the angular displacement given from the question as

$\theta = 0.2000 rev = 0.2000 rev * \frac{2 \pi \ rad }{1 rev}$

$=1.257\ rad$

$\alpha$ is the angular acceleration which is mathematically represented as

$\alpha = \frac{torque }{moment \ of \ inertia} = \frac{F_d * R_d}{I}$

The moment of inertial is mathematically represented as

$I = \frac{1}{2} m_dR^2_d$

Substituting values

$I = 0.5 * 40 * 0.200^2$

$= 0.8kg \cdot m^2$

Considering the equation for angular acceleration

$\alpha = \frac{torque }{moment \ of \ inertia} = \frac{F_d * R_d}{I}$

Substituting values

$\alph$ $\alpha = \frac{(30.0)(0.200)}{0.8}$

$= 7.5 rad/s^2$

Considering the equation for angular velocity

$w = \sqrt{2 \alpha \theta}$

Substituting values

$w =\sqrt{2 * (7.5) * 1.257}$

$= 4.34 \ rad/s$

The tangential velocity of a given point on the rim is mathematically represented as

$v = R_d w$

Substituting values

$= (0.200)(4.34)$

$v= 0.868 m/s$

The radial acceleration at hat point is mathematically represented as

$\alpha_r = \frac{v^2}{R}$

$= \frac{0.868^2}{0.200^2}$

$= 3.7699 \ m/s^2$

The tangential acceleration at that point is mathematically represented as

$\alpha _t = R \alpha$

Substituting values

$\alpha _t = (0.200) (7.5)$

$= 1.5 m/s^2$

The magnitude of resultant acceleration at that point is

$a = \sqrt{\alpha_r ^2+ \alpha_t^2 }$

Substituting values

$a = \sqrt{(3.7699)^2 + (1.5)^2}$

$a = 4.057 m/s^2$

7 0

3 years ago

Question 4 - If Angelica starts out at 30m/s, and in 16 s speeds up to 84 m/s, what is her acceleration?

Triss [41]

Answer:

C. $3.375 m/s^2$

Explanation:

The acceleration of an object can be found using the equation:

$a=\frac{v-u}{t}$

where

v is the final velocity

u is the initial velocity

t is the time it takes for the velocity to change from u to v

In this problem:

u = 30 m/s is the initial velocity of Angelica

v = 84 m/s is the final velocity

t is the time

Substituting into the equation, we find the acceleration:

$a=\frac{84-30}{16}=3.375 m/s^2$

4 0

3 years ago