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alukav5142 [94]
3 years ago
15

The cost of electricity varies widely throughout the United States; $0.120/kWh is a typical value. At this unit price, calculate

the cost of the following.
a. Leaving a 40.0-W porch light on for 2 weeks while you are on vacation.
b.Making a piece of dark toast in 3.00 min with a 980 W toaster.
c. Drying a load of clothes in 40.0 min in a 4900 W dryer.
Physics
1 answer:
strojnjashka [21]3 years ago
4 0

Answer: a) $1.6123 , b) $0.00588 c) $0.392

Explanation:

Note, all power in watts is converted to kilowatts and all units of time is converted to hours.

The cost of electricity is $0.12 for 1kwh.

Question a.

Power = 40w to kilowatts = 40/1000 = 0.04kw

Time = 2 weeks to hours = 24 * 14 = 336 h.

Energy = power * time.

Energy = 0.04 * 336 = 13.44kwh.

If 1kwh cost $0.12, then 13.44 kwh will cost

0.12 * 13.44 = $1.6132.

Question b

Power = 980w to kilowatts = 980/1000= 0.98kw

Time = 3 minutes to hours = 3/60 = 0.05 h

Energy = power * time

Energy = 0.98 * 0.05

Energy = 0.049kwh

If 1kwh cost $0.12, then 0.049 kwh will cost

0.049 * 0.12 = $0.00588

Question c

Power = 4900w to kilowatts = 4900/1000= 4.9kw.

Time = 40 minutes to hours = 40/ 60 = 0.67.

Energy = power * time

Energy = 4.9 * 0.67

Energy = 3.267 kwh

If 1 kwh cost $0.12, then 3.267kwh will cost

3.268 * 0.12 = $ 0.392

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May you help me answer this​
Firdavs [7]

1) See three Kepler laws below

2a) Acceleration is 2.2 m/s^2

2b) Tension in the string: 27.4 N

3a) Kinetic energy is the energy of motion, potential energy is the energy due to the position

3b) The kinetic energy of the object is 2.25 J

Explanation:

1)

There are three Kepler's law of planetary motion:

  1. 1st law: the planets orbit the sun in elliptical orbits, with the Sun located at one of the 2 focii
  2. 2nd law: a segment connecting the Sun with each planet sweeps out equal areas in equal time intervals. A direct consequence of this is that, when a planet is further from the sun, it travels slower, and when it is closer to the sun, it travels faster
  3. 3rd law: the square of the period of revolution of a planet around the sun is directly proportional to the cube of the semi-major axis of its orbit. Mathematically, T^2 \propto r^3, where T is the period of revolution and r is the semi-major axis of the orbit

2a)

To solve the problem, we have to write the equation of motions for each block along the direction parallel to the incline.

For the block on the right, we have:

M g sin \theta - T = Ma (1)

where

Mg sin \theta is the component of the weight of the block parallel to the incline, with

M = 8.0 kg (mass of the block)

g=9.8 m/s^2 (acceleration of gravity)

\theta=35^{\circ}

T = tension in the string

a = acceleration of the block

For the block on the left, we have similarly

T-mg sin \theta = ma (2)

where

m = 3.5 kg (mass of the block)

\theta=35^{\circ}

From (2) we get

T=mg sin \theta + ma

Substituting into (1),

M g sin \theta - mg sin \theta - ma = Ma

Solving for a,

a=\frac{M-m}{M+m}g sin \theta=\frac{8.0-3.5}{8.0+3.5}(9.8)(sin 35^{\circ})=2.2 m/s^2

2b)

The tension in the string can be calculated using the equation

T=mg sin \theta + ma

where

m = 3.5 kg (mass of lighter block)

g=9.8 m/s^2

\theta=35^{\circ}

a=2.2 m/s^2 (acceleration found in part 2)

Substituting,

T=(3.5)(9.8)(sin 35^{\circ}) +(3.5)(2.2)=27.4 N

3a)

The kinetic energy of an object is the energy due to its motion. It is calculated as

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

where

m is the mass of the object

v is its speed

The potential energy is the energy possessed by an object due to its position in a gravitational field. For an object near the Earth's surface, it is given by

U=mgh

where

m is the mass of the object

g is the strength of the gravitational field

h is the heigth of the object relative to the ground

3b)

The kinetic energy of an object is given by

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

where

m is the mass of the object

v is its speed

For the object in this problem,

m = 500 g = 0.5 kg

v = 3 m/s

Substituting, we find its kinetic energy:

K=\frac{1}{2}(0.5)(3)^2=2.25 J

Learn more about acceleration and forces:

brainly.com/question/11411375

brainly.com/question/1971321

brainly.com/question/2286502

brainly.com/question/2562700

And about kinetic energy:

brainly.com/question/6536722

#LearnwithBrainly

7 0
3 years ago
B. Jerome plays middle linebacker for South's varsity football team. In a game against
weqwewe [10]

Answer:

Option D

670 Kg.m/s

Explanation:

Initial momentum is given by mv=82*5.6=459.2 Kg.m/s (taking eastward as positive)

Final momentum is also mv but v being westward direction, we take it negative

Final momentum=82*-2.5= -205 Kg.m/s

Change in momentum=Final momentum-Initial momentum=-205-459.2=-664.2 Kg.m/s

Impulse=change in momentum=664.2 Kg.m/s rounded off as 670 Kg.m/s

4 0
3 years ago
Which planet has completed less than one orbit of the sun in the last 100 years?
OlgaM077 [116]
Since Pluto is no longer considered a planet, the correct answer would be Neptune. It is eight and farthest known planet of the Solar system. Orbital period of planet Neptune is 168 years. So planet Neptune has completed less than one orbit around the Sun in the last 100 years. 
6 0
3 years ago
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Permanent magnets consist of multiple _____
julsineya [31]

Answer: Permanent magnets consist of multiple "ferromagnetic materials" I think that might be the answer, there weren't really any choices for me to choose from.

3 0
3 years ago
Need help with this plz
Lisa [10]

Answer:

1 - amplification

3- actinide

5 - radioactive decay ( im not really sure on this one )

7- alternating current

Explanation:

7 0
3 years ago
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