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
Ipatiy [6.2K]
3 years ago
15

Number 29 plz help physics

Physics
1 answer:
svetoff [14.1K]3 years ago
8 0

Answer:

a. E = 900000 J = 900 KJ

b. ΔT = 8.18 °C

c. Cost = $ 7.2  

Explanation:

a.

The energy can be given by:

E = Pt

where,

E = Energy = ?

P = Power = 500 W

t = time = (0.5 h)(3600 s/1 h) = 1800 s

Therefore,

E = (500\ W)(1800\ s)

<u>E = 900000 J = 900 KJ</u>

b.

The change in temperature of room air is given by the following formula:

0.5E = mC\Delta T\\   (since 50% of energy is used to heat air)

where,

m = mass of air = 50 kg

C = specific heat of air = 1.1 KJ/kg.°C

ΔT = Change in temperature of air = ?

Therefore,

(0.5)(900\ KJ) = (50\ kg)(1.1\ KJ/Kg.^oC)\Delta T

<u>ΔT = 8.18 °C</u>

c.

First, we will calculate the total energy consumed:

E = (0.5\ KW)(6\ h/d)(30\ d)\\E = 90\ KWh

Now, for the cost:

Cost = (Unit\ Cost)(Energy)\\Cost = (\$ 0.08\KWh)(90\ KWh)

<u>Cost = $ 7.2</u>

You might be interested in
Which of the following statements are true at some time during the course of the motion? Check all that apply. Check all that ap
eduard

Answer:

The object can have zero velocity and, simultaneously, nonzero acceleration.

The object can have zero acceleration and, simultaneously, nonzero velocity.

The object can have nonzero velocity and nonzero acceleration simultaneously.

Explanation:

An object in simple harmonic motion has a total mechanical energy (sum of elastic potential energy and kinetic energy) that is constant:

E=U+K=1/2kx^2 + 1/2}mv^2

where,

k is equal to the spring constant

x is equal to the displacement

m is the mass

v is the speed

We can note that the force on the spring is given by Hook's law:

F=-kx

In Newton's law F = ma, this can be also be written as

ma=-kx

a=-k/mx

This implies that the acceleration is proportional to the displacement.

From the first equation, we can now states that:

When the displacement is zero, x=0, the acceleration is zero, a=0, and the velocity is maximum

When the velocity is zero, v=0, the acceleration is maximum, which occurs when the displacement is maximum

In all the other intermediate situations, both velocity and acceleration are nonzero.

So the correct answers are

The object can have zero acceleration and, simultaneously, nonzero velocity.

The object can have nonzero velocity and nonzero acceleration simultaneously.

The object can have zero velocity and, simultaneously, nonzero acceleration.

4 0
3 years ago
Read 2 more answers
What happens to a sheet of copper as kinetic energy of copper molecules decrease
liberstina [14]
First is melts then it expands next it gets cooler Finally it gains ener. Hope this helps you out.
8 0
3 years ago
What is an electromagnet ​
Svetllana [295]

Answer:

a soft metal core made into a magnet by the passage of electric current through a coil surrounding it.

Explanation:

5 0
3 years ago
The Venn diagram compares protons with neutrons. Which shared property belongs in the region marked "B"?
telo118 [61]

is there any choices?

4 0
3 years ago
Read 2 more answers
Think and discuss: Think about the process of finding the ideal conditions.A.Why would it be hard to find the ideal light intens
Agata [3.3K]

Answer:

The environmental conditions prevent the reaction to be accurate.

Explanation:

If the temperature is very hot then the oxygen production will be low even near to zero then the accurate light intensity can not be determined. The oxygen production level goes down when the temperature is too hot. The oxygen production is maximized when the temperature is around 25 degree Celsius. When the intensity of light is increased to 40% then the oxygen production will increase.

5 0
3 years ago
Other questions:
  • With mechanical waves, what is moving and what stays in roughly the same place?
    11·1 answer
  • A man inside an insulated metallic cage does not receive shock when the cage is highly charge .explain.
    7·1 answer
  • In electromagnetic waves, frequency is inversely proportional to what?
    10·1 answer
  • When you throw a pebble straight up with initial speed V, it reaches a maximum height H with no air resistance. At what speed sh
    7·1 answer
  • A fisherman notices that his boat is moving up and down periodically, owing to waves on the surface of the water. It takes 2.5 s
    7·1 answer
  • Which device manages the flow of current in an electric circuit?
    14·2 answers
  • Click to review the online content. Then answer the question(s) below, using complete sentences. Scroll down to view additional
    10·2 answers
  • A boy travels 12km east wards to a point B and then 5km southwards to another point C. Calculate the difference between the magn
    8·1 answer
  • In the bohr model, what is the ratio of its kinetic energy to its potential energy?
    10·1 answer
  • A 5.0 kg book is lying on a 0.25 meter high table.
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!