1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Ivan
3 years ago
9

A 300-kg piano being held by a crane is accidentally dropped from a height of 15 meters. a. What is the speed of the piano just

before it hits the ground? b. How much energy is dissipated when the piano hits the ground? c. What are some indicators of this release of energy that could be observed during and shortly after the piano hits the ground? d. Suppose that a parachute is used to slow the fall of the piano. i. How would the amount of kinetic energy dissipated by the ground change? Explain. ii. How would the total amount of energy dissipated change? Explain.

Physics
1 answer:
FinnZ [79.3K]3 years ago
3 0

Answer:

a) 17.16m/s

b) 44,145J

c) Sound the piano makes when hitting the ground, vibration of the ground, heat.

d) i) It's smaller due to the energy dissipated by the friction between air and the parachute.

ii) It stays the same, the only difference is that the dissipated energy is distributed between air resistance and the kinetic energy dissipated by the ground whent he piano hits it.

Explanation:

a)

In order to solve this problem we must start by doing a drawing of the situation, which will help us visualize the problem better. (See attached picture).

So, in this problem we can ignore air resistance so we can say that the energy is conserved, this is the total initial energy is the same as the total final energy, so we get that:

U_{0}+K_{0}=U_{f}+K_{f}

When the piano is released it has an initial speed of zero, so the initial kinetic energy is zero. When the piano hits the ground it will have a height of 0m, so the final potential energy is zero as well. This will simplify our equation:

U_{0}=K_{f}

We know that potential energy is given by the formula:

U=mgh

and kinetic energy is given by the formula:

K=\frac{1}{2}mv^{2}

which can be substituted in our equation:

mgh=\frac{1}{2}mv^{2}

we can divide both sides of the equation into the mass of the piano, so we get:

gh=\frac{1}{2}v^{2}

which can be solved for the final velocity which yields:

v=\sqrt{2gh}

we can now substitute the data provided by the problem so we get:

v=\sqrt{2(9.81m/s^{2})(15m)}

which yields:

v=17.16m/s

b)

Since energy is conserved, this means that the total dissipated energy will be the same as the potential energy, so we get that:

E=mgh

so

E=(300kg)(9.81m/s^{2})(15m)

which yields:

E=44,145J

c)

When the piano hits the ground, the kinetic energy it had will be transformed to other types of energy, mostly vibration and heat. The vibration will turn to sound due to the movement of air created by the piano itself and the ground. And heat is created by the friction between the molecules created by the vibrations and the collition itself. So some of the indicators of this release of energy could be:

-Sound

-Vibration

-Heat.

d)

i) The amount of inetic energy dissipated would decrease due to the friction between air and the parachute. Since air is resisting the movement of the piano, this will translate into a loss of energy, if we did an energy balance we would get that:

U_{0}=K_{f}+E_{p}

The total amount of energy is conserved but it will be distributed between the energy lost due to air resistance and the kinetic energy the piano has at the time it hits the ground.

ii) So the total amount of energy dissipated remains the same, the only difference is that it will be distributed between air resistance and the kinetic energy of the piano.

You might be interested in
A well lagged copper calorimeter of mas 120g contains 70g of water and 10g ice both at 0°C . Dry steam at 100°C is passed in unt
Lina20 [59]

Answer:

7.6 g

Explanation:

"Well lagged" means insulated, so there's no heat transfer between the calorimeter and the surroundings.

The heat gained by the copper, water, and ice = the heat lost by the steam

Heat gained by the copper:

q = mCΔT

q = (120 g) (0.40 J/g/K) (40°C − 0°C)

q = 1920 J

Heat gained by the water:

q = mCΔT

q = (70 g) (4.2 J/g/K) (40°C − 0°C)

q = 11760 J

Heat gained by the ice:

q = mL + mCΔT

q = (10 g) (320 J/g) + (10 g) (4.2 J/g/K) (40°C − 0°C)

q = 4880 J

Heat lost by the steam:

q = mL + mCΔT

q = m (2200 J/g) + m (4.2 J/g/K) (100°C − 40°C)

q = 2452 J/g m

Plugging the values into the equation:

1920 J + 11760 J + 4880 J = 2452 J/g m

18560 J = 2452 J/g m

m = 7.6 g

7 0
3 years ago
If the mass of a material is 99 grams and the volume of the material is 22 cm3, what would the density of the material be?
Kazeer [188]
You are asked to give the answer in <span>g/cm3. So without knowing any single formulae you can just divide grams by cm3. 

</span>\frac{99 grams}{22 cm^{3} }

 = 4.5 g/cm3
7 0
3 years ago
A wheel moves in the xy plane in such a way that the location of its center is given by the equations xo = 12t3 and yo = R = 2,
Stella [2.4K]

Answer:

the velocity of the point P located on the horizontal diameter of the wheel at t = 1.4 s  is   P =  104.04 \hat{i} -314.432 \hat{j}

Explanation:

The free-body  diagram below shows the interpretation of the question; from the diagram , the wheel that is rolling in a clockwise directio will have two velocities at point P;

  • the peripheral velocity that is directed downward (-V_y) along the y-axis
  • the linear velocity (V_x) that is directed along the x-axis

Now;

V_x = \frac{d}{dt}(12t^3+2) = 36 t^2

V_x = 36(1.7)^2\\\\V_x = 104.04\ ft/s

Also,

-V_y = R* \omega

where \omega(angular velocity) = \frac{d\theta}{dt} = \frac{d}{dt}(8t^4)

-V_y = 2*32t^3)\\\\\\-V_y = 2*32(1.7^3)\\\\-V_y = 314.432 \ ft/s

∴ the velocity of the point P located on the horizontal diameter of the wheel at t = 1.4 s  is   P =  104.04 \hat{i} -314.432 \hat{j}

3 0
3 years ago
One normal afternoon in undisclosed City X, the chocolate factory workers overload the Easter egg machine. A group of angsty tee
musickatia [10]

Answer:

The correct option is;

C. 1,715 m

Explanation:

We are given the information from the group of teen at the City edge

Time of arrival of explosion sound = 5 s after sighting

Time of sighting explosion = 5 s before hearing the boom

Speed of sound in air ≈ 343 m/s

Speed of light = 299,792 km/s

Therefore, distance covered by sound in 5 seconds is given by the following equation;

Speed = \frac{Distance}{Time}

\therefore 343 \ m/s= \frac{Distance}{5 \, s}

Hence Distance = 343 m/s × 5 s = 1715 m

To check, we compare the time it would take for the light to cover 1715 m

That is Time = \frac{Distance}{Speed} =  \frac{1715}{299,792,000} = 0.00000572 \, s which is instantaneous hence the distance can be approximated by the time duration for the speed of sound.

Therefore, the distance of the students from the factory is approximately 1,715 m

8 0
3 years ago
What is the prefix for oxygen in As2O5? tri- di- mono- penta-
ikadub [295]
The prefix for oxygen in As2O5 is PENTA. 
Penta is used to show that the number of oxygen atoms present in the compound is five. Penta means five, while mono mean one, di means two, tri means three and tetra mans four and so on. The chemical name for the given compound is Arsenic pentoxide.
3 0
3 years ago
Read 2 more answers
Other questions:
  • If you want to know your speed going from point A to point B, what
    9·1 answer
  • if the distance between two objects is doubled, the force of gravitation between them becomes __________ of initial value.
    6·1 answer
  • What is the change in velocity if the final velocity is 80 mph and the initial velocity is 20 mph? Is the object speeding up or
    7·1 answer
  • Why are atoms electrically neutral?
    8·1 answer
  • A gnat takes off from one end of a pencil and flies around erratically for 41.641.6 s before landing on the other end of the sam
    12·1 answer
  • Name the nutrients required for the<br>body.​
    5·1 answer
  • #1- How much Magnesium is consumed in this reaction? *input # only.
    11·1 answer
  • Ions form bonds by __________ electrons.
    12·2 answers
  • Give a few examples/ applications of the universal law of gravitation​
    12·1 answer
  • 3. True or false. All objects that are made of metal<br> are magnetic. Explain why or why not.
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!