Physics, 21.10.2020 16:01 gmoney58

A 6 gram coin is which is initially at rest is dropped from the observation deck of a skyscraper 300 meters above the street below. Required:
a. What is the work done by gravity on the coin as it falls?
b. Because there is air resistance the coin was slowed and hit the ground with a final velocity of 60 m/s. What is the kinetic energy of the coin at this speed? Joules
c. How much work was lost to air resistance as the coin fell? Joules
d. What is the average force exerted on the coin due to the air resistance as it fell?

Answers: 1

Show answers

Answers

Answer from: emilyf05

a) The work done by gravity on the coin as it falls is 17.653 joules.

b) The kinetic energy of the coin at a speed of 60 meters per second is 10.8 joules.

c) The work lost due to air resistance is 6.853 joules.

d) The average force exerted on the coin due to air resistance as it fell is 0.023 newtons.

Explanation:

a) We must remind that situation with Earth-coin system must be represented by Principle of Energy Conservation and Work Energy Theorem. According to this latter, work done by gravity equals to the change in gravitational potential energy:

$\Delta U_{g} = m\cdot g \cdot \Delta z$ (Eq. 1)

Where:

$\Delta U_{g}$ - Change in gravitational potential energy, measured in joules.

- Mass, measured in kilograms.

- Gravitational accelerations, measured in meters per square second.

$\Delta z$ - Height of the skyscraper, measured in meters.

If we know that $m = 0.006\,kg$ , $g = 9.807\,\frac{m}{s^{2}}$ and $\Delta z = 300\,m$ , the work done gravity on the coin is:

$\Delta U_{g} = (0.006\,kg)\cdot \left(9.807\,\frac{m}{s^{2}} \right)\cdot (300\,m)$

$\Delta U_{g} = 17.653\,J$

The work done by gravity on the coin as it falls is 17.653 joules.

b) By definition of translation kinetic energy, we get the following model:

$K = \frac{1}{2}\cdot m\cdot v^{2}$

Where:

- Kinetic energy of the coin right before hitting the street, measured in joules.

- Speed of the coin, measured in meters per second.

If we get that $m = 0.006\,kg$ and $v = 60\,\frac{m}{s}$ , the kinetic energy at this speed is:

$K = \frac{1}{2}\cdot (0.006\,kg)\cdot \left(60\,\frac{m}{s} \right)^{2}$

$K = 10.8\,J$

The kinetic energy of the coin at a speed of 60 meters per second is 10.8 joules.

c) The work lost due to air resistance is obtained derived from Principle of Energy Conservation and Work-Energy Theorem:

$W_{lost} = \Delta U_{g}-K$ (Eq. 2)

Where $W_{lost}$ is the work lost due to air resistance, measured in joules.

If we know that $\Delta U_{g} = 17.653\,J$ and $K = 10.8\,J$ , the work lost due to air resistance is:

$W_{lost} = 17.653\,J-10.8\,J$

$W_{lost} = 6.853\,J$

The work lost due to air resistance is 6.853 joules.

d) The average force exerted on the coin due to air resistance can be determined by applying definition of work, as air resistance force was antiparallel to the displacement of the coin. That is:

$W_{lost} = F\cdot \Delta z$

$F = \frac{W_{lost}}{\Delta z}$ (Eq. 3)

Where is the average force exerted on the coin due to air resistance, measured in newtons.

If we know that $W_{lost} = 6.853\,J$ and $\Delta z = 300\,m$ , then the average force exerted on the coin is:

$F = \frac{6.853\,J}{300\,m}$

$F = 0.023\,N$

The average force exerted on the coin due to air resistance as it fell is 0.023 newtons.

Answer from: Quest

the part of the wave he is travelling on is the crest

Answer from: Quest

Did you ever figue this

Another question on Physics

Physics, 22.06.2019 01:30

Afigure skater is rotating at a rate of 200 revolutions per minute. what is the angular speed, in units of rad/s? 20.9 12000 200 3.33

Answers: 2

Answer

Physics, 22.06.2019 10:30

Light from a sodium lamp passes through a diffraction grating that has 1000 slits per millimeter. the interference pattern is viewed on a screen 1.000 m behind the grating. the first (m = 1) two bright yellow fringes that are visible are 0.7288 m and 0.7300 m from the central maximum. what are the wavelengths of these two fringes?

Answers: 2

Answer

Physics, 22.06.2019 18:30

Abaseball is thrown from the outfield toward the catcher. when the ball reaches its highest point, which statement is true? (a)its velocity is not zero, but its acceleration is zero. (b) its velocity and its acceleration are both zero. (c) its velocity is perpendicular to its acceleration. (d) its acceleration depends on the angle at which the ball was thrown. (e) none of the above statements are true.

Answers: 1

Answer

Physics, 22.06.2019 22:00

Ais not a mixture. colloid compound suspension solution

Answers: 1

Answer

You know the right answer?

A 6 gram coin is which is initially at rest is dropped from the observation deck of a skyscraper 300...

Questions