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marshall27 [118]
3 years ago
6

We often use a spoon to cool coffee by stirring. Some of the heat is conducted from the coffee to the air by this method, but th

e spoon itself will cool the coffee a little. If a 12 gram aluminum teaspoon at 22 o C is placed in 175 ml of water (coffee's specific heat is close to water's) at 85 o C, what will the final temperature be? (Other factors, such as heat transfer to the air, may be ignored.)
Question 23 options:

78oC

92oC

84o C

82oC
Physics
1 answer:
Ilia_Sergeevich [38]3 years ago
3 0

Answer:

Explanation:

heat lost by coffee = heat gain by aluminum spoon

heat lost by coffee = mc ( 85° C - T)

175 ml of water = 175 grams

175 grams = (175 / 1000) kg = 0.175 kg

heat loss by coffee = 0.175 × 4182 J/Kgk ( 85 - T) = 731.85 ( 85-T) = 62207.25 - 731.85 T

heat gain by aluminum spoon = 0.012kg × 897 J/kgK ( T - 22) = 10.764 T - 236.808

10.764 T - 236.808 = 62207.25 - 731.85 T

10.764 T + 731.85 T = 62207.25 + 236.808

T = 84.086 ° C approx 84°C

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Answer:

Explanation:

u =  150 m/s

R = 800 m

The formula for the horizontal range is

R=\frac{u^{2}Sin2\theta }{g}

where, θ is angle of projection.

800=\frac{150^{2}Sin2\theta }{9.8}

Sin2θ = 0.348

2θ = 20.4°

θ = 10.2°

The range is same for the complementary angles.

So, the other angle is 90 - 10.2 = 79.8°

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Date: 12-3-21<br> 4.<br> The momentum of a 5-kilogram object moving at<br> 6 meters per second is
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Answer

30 kg . m/sec

Explanation:

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2 years ago
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A 95 kg fullback, running at 8.2 m/s, collides in midair with a 128 kg defensive tackle moving in the opposite direction. Both p
Sindrei [870]
Thank you for posting your question here at brainly. I hope the answer will help you. Feel free to ask more questions here.

Below is the answers:

Fullback running 

<span>Mo = mass * velocity </span>
<span>Mo = 95kg * 8.2 m/s =779 kg*m/s (a </span>

<span>He got stopped Change in Mo = 779 kg*m/s (b </span>

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3 years ago
The base of a right prism is a rhombus with diagonals of 6 and 8. If the altitude of the prism is 12, what is the total surface
Agata [3.3K]

Answer:

total surface area is 432

Explanation:

Given data

base  = 6

diagonals = 8

altitude = 12

to find out

total surface area

solution

we know total surface area of prism is

total surface area = lateral surface area + 2base area  ..............1

so

first we calculate base perimeter i.e = 2 length + 2 width

so perimeter = 2(8) + 2(6) = 25

and area  = length * width = 8*6 = 48

so lateral surface area is perimeter * height i.e

lateral surface area = 28* 12

lateral surface area = 336

put this value in equation 1 we get

total surface area = lateral surface area + 2base area

total surface area = 336 + 2(48)

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3 years ago
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One speaker generates sound waves with amplitude A.
raketka [301]

Answer:

iv) It is 9x bigger than before

Explanation:

As the amplitudes of the new speakers add directly with the original one, taking into account the phase that they have, the composed amplitude of the sound wave is as follows:

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The intensity of the wave, assuming it propagates evenly in all directions, is constant at a given distance from the source, and can be expressed as follows:

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If the amplitude changes increasing three times, the change in intensity will be proportional to the square of the change in amplitude, i.e., it will be 9 times bigger.

So, the statement iv) is the right one.

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3 years ago
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