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Vika [28.1K]
3 years ago
8

A 12.0 kg rock slides off the edge of a bridge and falls into the water 25.0 meters below. what is the kinetic energy of the roc

k just as it hits the water?
Physics
1 answer:
Pavel [41]3 years ago
7 0
During the fall, all the initial potential energy of the rock 
U=mgh
has converted into kinetic energy of motion
K= \frac{1}{2}mv^2
where h is the initial height of the rock, m its mass, and v its velocity just before hitting the water. So, for energy conservation, we have
U=K
and so we can find the value of K, the kinetic energy of the rock just before hitting the ground:
K=U=mgh = (12.0 kg)(9.81 m/s^2)(25.0 m)=2943 J
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Explain whether demand is likely to be elastic or inelastic for Big Macs. A. Elastic comma since many other fast food items coul
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Answer:

A - elastic since many other fast food items could be considered close substitutes.

Explanation:

The price elasticity of demand is how much the demand of the Big Macs will change due to a 1% change in price. Should the elasticity be greater than 1, the Big Macs will be elastic. Should it be less than 1, the Big Macs are inelastic.  

Demand elasticity is calculated as the percentage change in quantity demanded divided by a percentage change in price.

Since Big Macs are (i) a luxury good, and (ii) have close substitutes (other burgers available at McDonalds and other fast food stores), we will say their elasticity is greater than 1.  

This means that the demand of Big Macs will change due to a 1% increase in price due to the presence of close substitutes.  

3 0
3 years ago
Which players are usually the tallest on their team, and stay close to the basket so they can shoot and rebound the ball?
alexdok [17]

Answer:

Center

Explanation:

The center is the tallest player on each team, playing near the basket. On offense, the center tries to score on close shots and rebound. But on defense, the center tries to block opponents' shots and rebound their misses.

7 0
3 years ago
Examine the spectra of the four unknown substances shown below. What can you conclude?
NARA [144]
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7 0
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Is a neutron star also a black hole?
coldgirl [10]

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A black hole is the remains of a star that had enough mass to go even farther
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and can't describe, and occupies zero volume.

Contrary to popular fairy tales, a black hole doesn't reach out and "suck things in".
It's just so small (zero) that things can get very close to it.  You know that gravity
gets stronger as you get closer to an object, so if the object has no size at all, you
can get really really close to it, and THAT's where the gravity gets really strong.
You may weigh, let's say, 100 pounds on the Earth.  But you're like 4,000 miles
from the center of the Earth.  What if all of the earth's mass was crammed into
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8 0
3 years ago
Jupiter's moon Io has active volcanoes (in fact, it is the most volcanically active body in the solar system) that eject materia
kramer

Answer:

The height reached by the material on Earth is 91 km.

Explanation:

Given that,

Mass M_{Io}=8.93\times10^{22}\ kg

Radius = 1821 km

Height h_{Io}=500\ km

Suppose we need to find that how high would this material go on earth if it were ejected with the same speed as on Io?

We need to calculate the acceleration due to gravity on Io

Using formula of gravity

g =\dfrac{GM_{Io}}{(R_{Io})^2}

Put the value into the formula

g=\dfrac{6.67\times10^{-11}\times8.93\times10^{22}}{(1821\times10^{3})^2}

g=1.79\ m/s^2

Let  v be the speed at which the material is ejected.

We need to calculate the height

Using the formula of height

H=\dfrac{v^2}{2g}

Using ratio of height of earth and height of Io

\dfrac{H_{e}}{H_{Io}}=\dfrac{\dfrac{v^2}{2g_{e}}}{\dfrac{v^2}{2g_{Io}}}

\dfrac{H_{e}}{H_{Io}}=\dfrac{g_{Io}}{g_{e}}

Put the value into the formula

\dfrac{H_{e}}{H_{Io}}=\dfrac{1.79}{9.8}

\dfrac{H_{e}}{H_{Io}}=0.182

H_{e}=0.182\times H_{Io}

H_{e}=0.182\times500

H_{e}=91\ km

Hence, The height reached by the material on Earth is 91 km.

3 0
3 years ago
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