Answer:
<em>Both energies are equal when the rock has fallen 20 m or equivalently when it is at a height of 20 m.</em>
Explanation:
<u>Potential and Kinetic Energy</u>
The gravitational potential energy is the energy an object has due to its height above the ground. The formula is
Where:
m = mass of the object
g = acceleration of gravity (9.8~m/s^2)
h = height
Note we can also use the object's weight W=mg into the formula:
The kinetic energy is the energy an object has due to its speed:
Where v is the object's speed.
Initially, the object has no kinetic energy because it's assumed at rest.
The W=30 N rock falls from a height of h=40 m, thus:
Since the sum of the kinetic and potential energies is constant:
U' + K' = 1,200 J
Here, U' and K' are the energies at any point of the motion. Since both must be the same:
U' = K' = 600 J
U'=Wh'=600
Solving for h':
Both energies are equal when the rock has fallen 20 m or equivalently when it is at a height of 20 m.
when observer and source moves relative to each other then the frequency received by the observer is different from the real frequency
This apparent change in frequency due to relative motion is known as Doppler's effect.
Here we know that
here we know that
= real frequency
v = speed of sound
= speed of observer
= speed of source
so this is known as Doppler's Effect
A white dwarf cannot support its own weight by its degenerate pressure if its mass is greater than 1.4 solar masses.
<h3>
What are white dwarfs?</h3>
White dwarfs are stellar core remnant composed mostly of electron-degenerate matter.
White dwarf is very dense due to its large mass and smaller volume.
<h3>Reasons for comparable mass of white dwarfs and Sun</h3>
- Stars with main sequence masses less than about 0.5 solar masses cannot ignite the helium fusion required to become white dwarfs.
- A white dwarf cannot support its own weight by its degenerate pressure if its mass is greater than 1.4 solar masses.
Learn more about white dwarfs here: brainly.com/question/24873876
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motion
vt=vo+at
10 m/s = 2 m/s + 2.2 m/s².t
8 = 2.2t
