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amm1812
2 years ago
7

A motor is used to lift a 10 kg mass 2 m above the ground in 4 s. If the power input to the motor is 100 W. what is the efficien

cy of the motor?
(Show Work)
Physics
1 answer:
Bad White [126]2 years ago
7 0

Answer:

98%

Explanation:

Given parameters

Mass of motor = 10kg

Height = 2m

Time = 2s

Power input = 100w

Unknown

Efficiency = ?

Solution

Efficiency is the percentage of the power output to the power input.

Power is the rate at which work is done.

Power output = mass x g x height / time

g is the acceleration due to gravity

Power output = 10x 2 x 9.8 / 2 = 98W

Efficiency = power output/ power input x 100

Efficiency = 98/100 x 100 = 98%

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In the united states a standard letter sized piece of paper is 8.5 inches wide by 11 inches long. The international standard for
Andre45 [30]

This question is incomplete

Complete Question

In the United States, a standard letter-sized piece of paper is 8.5 inches wide by 11 inches long. The international standard for a letter-sized piece of paper is different. The international standard is based on SI units: 21.0 cm wide by 29.7 cm long.

a. Convert 21.0 cm to inches. Show your dimensional analysis setup.

b. Convert 29.7 cm to inches. Show your dimensional analysis setup.

c. State the dimensions, in inches, of the international standard for a letter-sized piece of paper.

d. Which piece of paper is longer: a U.S. letter-sized piece of paper, or an international letter-sized piece of paper?

Answer:

a) 8.267721 inches ≈ 8.3 inches

b) 11.6929197 inches ≈ 11.7 inches

c) It's dimensions in inches for the international standard for letter - sized for paper = 8.3 wide inches by 11.7 inches long

d) The International standard letter - sized paper is longer.

Explanation:

a. Convert 21.0 cm to inches. Show your dimensional analysis setup.

1 cm = 0.393701inch

21 cm =

Cross Multiply

21 cm × 0.393701inch/ 1 cm

= 8.267721 inches

Approximately 8.3 inches

b. Convert 29.7 cm to inches. Show your dimensional analysis setup.

1 cm = 0.393701inch

29.7 cm =

Cross Multiply

29.7 × 0.393701 inch/ 1 cm

= 11.6929197 inches

Approximately 11.7 inches

c. State the dimensions, in inches, of the international standard for a letter-sized piece of paper.

The international standard for a letter-sized has dimensions 21.0 cm wide by 29.7 cm long.

Where

21.0cm = 8.267721 inches

≈ 8.3 inches

29.7cm = 11.6929197 inches

≈ 11.7 inches

Hence, it's dimensions in inches = 8.3 inches by 11.7 inches.

d. Which piece of paper is longer: a U.S. letter-sized piece of paper, or an international letter-sized piece of paper?

U.S letter - sized paper = 8.5 inches wide by 11 inches long

International standard letter- sized paper = 8.3 wide inches by 11.7 inches long.

Hence, the International standard letter - sized paper is longer.

5 0
3 years ago
Two children are balanced on a seesaw that has a mass of 18.0 kg. The first child has a mass of 26.0 kg and sits 1.60 m from the
Mashcka [7]

Answer:

1.28 m

Explanation:

As shown in the diagram attached,

According to the principle of moment,

For a body at equilibrium,

Sum of clockwise moment = sum of anticlockwise moment.

Taking moment about the pivot,

W₁(1.6)+W(0.133) = W₂(x)............... Equation 1

Where W₁ = Weight of the first child, Wₓ = Weight of the seesaw, W₂ = weight of the second child, x = distance of the second child from the pivot.

But,

W = mg

Where g = 9.8 m/s², m = mass of the body

Therefore,

W₁ = 26×9.8 = 254.8 N,

Wₓ = 18×9.8 = 176.4 N

W₂ = 34.4×9.8 = 337.12 N

Substitute these values into equation 1

(254.8×1.6)+(176.4×0.133) = 337.12(x)

407.68+23.4612 = 337.12x

337.12x = 431.1412

x = 431.1412/337.12

x = 1.2789

x ≈ 1.28 m

7 0
2 years ago
Which image illustrates why dark clothing helps to keep you warm on a cool, sunny day?
xeze [42]

Answer:

Explanation:

I suppose it has to do with the way the diagram is drawn. The heat does not reflect which makes both A and B incorrect.

C would have nothing to do with either reflection or refraction.

That only leaves D which is the answer.

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3 years ago
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What are three things we should try to limit that we may find on a food label.
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Answer:

Added sugars, Saturated fat, Trans fat.

Explanation:

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3 years ago
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Adjectives for the word probable are......
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the answer for the question is D. all of the above

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