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tatiyna
2 years ago
8

Many college students have a mini-fridge in their dorm room. A standard mini fridge costs roughly $100, uses about 100 watts of

electricity per hour when it is running, and can be expected to last for 5 years. The refrigerator is plugged into an electrical socket 24 hours a day, but is usually running only about 12 hours per day. Assume that electricity costs $0.10/kWh.
(a) Calculate the lifetime monetary cost of owning and operating the refrigerator.
(b) Assume that the electricity used to power the refrigerator comes from a coal-burning power plant. One metric ton of coal contains 29.3 GJ (8,140 kWh) of energy. Because of the inefficiency of electricity generation and transmission, only one-third of the energy in coal reaches the refrigerator. How many tons of coal are used to power the refrigerator during its lifetime?
(c) Assume that 15 percent of the mass of the coal burned in the power plant ends up as coal ash, a potentially toxic mixture that contains mercury and arsenic. How many tons of coal ash are produced as a result of the refrigerator's electricity use over its lifetime?
(d) What externalities does your answer from part (a) not include? Describe one social and one environmental cost associated with using this appliance.
(e) Describe two ways a college student could reduce the electricity use associated with having a mini fridge in his or her dorm room.
Physics
1 answer:
borishaifa [10]2 years ago
4 0

The amount of coal burnt to operate the mini fridge is 0.81 metric tons.

<h3>What is energy cost?</h3>

The term energy cost refers to the monetary cost of operating a particular electrical appliance. Let us now answer the questions one after the other.

a) Power consumption per hour = 100 watt or 0.1kW. To operate it for an hour we have  0.1kWhr × $0.10/kWh = 0.01$ Since it operates for twelve hours a day 12(0.01$)= 0.12$ per day. In five years; 0.12$× 5 × 365 = 219 $.

b) Electricity used for the five years = 5 × 365 × 12 × 0.1kWhr = 2190 kWhr

Since 1 metric ton of coal produces 2713 kWh(considering energy losses)

x metric tons of coal produces 2190 kWhr

x = 1 metric ton × 2190 kWhr/2713 kWh

x = 0.81 metric tons

c) In part 1 we did not include the cost of the environmental damage caused by the mining of coal and the social inconveniences caused by the sound of the mini fridge.

d) The college student could reduce the electricity use associated with having a mini fridge in his or her dorm room by turning it off for some hours within the day.

Learn more about cost of electricity: brainly.com/question/13498414

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What is the magnification of an astronomical telescope whose objective lens has a focal length of 71 cm and whose eyepiece has a
Rus_ich [418]

To solve this problem it is necessary to apply the concepts related to optical magnification (is the process of enlarging the apparent size, not physical size, of something.). Specifically the angular magnification of an optical telescope is given by

M = -\frac{f_o}{f_e}

Where,

f_o = Focal length of the objective lens in a refractor

f_e = Focal length of the eyepiece

Our values are given as

f_o = 71cm

f_e =  2.1cm

Replacing we have

M = -\frac{f_o}{f_e}

M = -\frac{71}{2.1}

M = - 33.81

Therefore the magnification of this astronomical telescope is -33.81

7 0
3 years ago
A 20 g bullet is shot from a 10 kg gun with a velocity of 400 m/s. What
Nady [450]

Answer: -.80m/s

Explanation:

3 0
3 years ago
1. ¿Qué presión se ejerce sobre cada una de las cuatro patas de una mesa si su masa es de 20 kg y
mestny [16]
Tenemos.

Masa de la mesa = 20kg
Masa encima = 10kg
Masa total = 30kg
Area de cada pata = 20cm² = 20cm² * 1/10000cm² * 1m² =0,002m²

Presió(P)n que se ejerce sobre cada pata.

P =F/A
P = Masa por gravedad/A Masa = 30kg Gravedad =9,8m/s²
P =(30kg * 9,8m/s²)/0,002m²
P = 294kg * m/s²/0,002m² Pero kg *m/s² = Nw
P = 294Nw0,002m²
P = 147000 Nw/m² Pero Nw/m² = pa
p =1,47 * 10⁵ pa

Respuesta.
La presión que se ejerce sobre cada pata es de 1,47 * 10⁵pa
8 0
2 years ago
U need help so can some one help me
GrogVix [38]

Answer:

are sure this is a question

7 0
2 years ago
An astronaut has a momentum of 280 kg and travels 10 m/s. what is the mass of the astronaut?
Kamila [148]

Answer:

The answer is

<h2>28 kg</h2>

Explanation:

The mass of an object given it's momentum and velocity / speed can be found by using the formula

m =  \frac{p}{v}  \\

where

m is the mass

p is the momentum

v is the speed or velocity

From the question

p = 280 kg/ms

v = 10 m/s

The mass of the object is

m =  \frac{280}{10}  = 28 \\

We have the final answer as

<h3>28 kg</h3>

Hope this helps you

3 0
3 years ago
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