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erma4kov [3.2K]
3 years ago
7

A 3.00 watt electric motor is plugged into an electrical outlet It takes the motor 30 00 seconds to lift a mass of 254.9 g a dis

tance of
10.00 cm. In that time, the motor has used 90.00 J of energy Assuming no energy leaves the system, how much heat has been
added to the system by the end of those 30 seconds?​
Physics
1 answer:
trasher [3.6K]3 years ago
8 0

Answer:

89.75 J

Explanation:

The motor uses 90.00 J of electrical energy.  Any of that energy that isn't used to do work is converted to heat.

The amount of work done is:

W = mgh

W = (0.2549 kg) (9.81 m/s²) (0.1000 m)

W = 0.2501 J

So the heat generated is:

Q = 90.00 J − 0.2501 J

Q = 89.75 J

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Newton's law of cooling states that the temperature of an object changes at a rate proportional to the difference between its te
schepotkina [342]

Answer:

6.77 minutes

Explanation:

172 degree - 78 degree = (185 degree - 78 degree)e−2 k

=> 94 = 107

e−2 k => 94 ÷ 107

k => ln (94÷107) / 2

147 - 78 = (185 - 78)e ^[ln (94÷107) / 2]

=> 69 = 107 e^ [ln (94÷107) / 2]

e^[ln (94÷107) / 2] =69 ÷ 107

=> t = [ln (69 ÷ 107)] ÷ [ln (94÷107) / 2]

t=> -0.4387 ÷ -0.0648

t => 6.77 minutes.

Therefore, the final answer to the question is 6.77 minutes.

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2 years ago
People's perceptions of what is important in life are known as:
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Social perception (or person perception) is the study of how people form impressions of and make inferences about other people as sovereign personalities.A real-world example of social perception is understanding that others disagree with what one said when one sees them roll their eyes.
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3 years ago
Areas near oceans have ______________________ than areas in the interior of continents because of the great storage capacity of
zhenek [66]
The answer would be more mass

7 0
3 years ago
An 11.0-W energy-efficient fluorescent lightbulb is designed to produce the same illumination as a conventional 40.0-W incandesc
mario62 [17]

Answer:

Savings = $0.709

Explanation:

Energy consumed by 11 W energy efficient fluorescent bulb is given as

E = Power \times time

now we can say

E = 11 \times 220h

E = 2.42 kWh

now total cost of the energy used is given as

Amount = 2.42 \times $0.111

Amount = $0.268

Now for conventional 40 W bulb  we can say

E = Power \times time

now we can say

E = 40.0 \times 220h

E = 8.8 kWh

now total cost of the energy used is given as

Amount = 8.8 \times $0.111

Amount = $0.977

So total money saving is given as

Savings = $0.977 - $0.268

Savings = $0.709

5 0
3 years ago
A rifle can shoot a 4.20-g bullet at a speed of 965 m/s.a)Find the KE of the bullet at this speed.b) What work is done on the bu
olga55 [171]

Answer:

a)  1955.6 J

b) 1955.6 J

c) 2607 N

d) 110373 J

Explanation:

a) Kinetic\ Energy = \frac{1}{2} mv^2 = \frac{1}{2} \times  \frac{4.2}{1000} \times  965^2 = 1955.6 J

b) Work done on bullet should be increase in KE = 1955.6 J

c) Work done = Force \times displacement = KE of bullet

              F = \frac{1955.6}{0.75} = 2607 N

d) Work done to stop = KE = F_{stop} \times d_{stop}

F_{stop} = \frac{1955.6}{\frac{1.5}{100}} = 110373 J

6 0
3 years ago
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