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4 years ago

The air in a kitchen has a mass of 60.0kg and a specific heat of 1505J/(kg°C).

Physics

2 answers:

BARSIC [14]4 years ago

8 0

Your answer is 632,100J which is Choice D

AveGali [126]4 years ago

5 0

Answer: The answer is D.

So you have 60kg of air, and the specific heat per kilogram is 1505j/(kg°C), this means you need 1505j to increase 1°C to the temperature of a mass of 1kg of air.

So, if the change in temperature is from 24°C to 31°C, you are increasing 7°C to 60kg of air.

then, for each degree you need 60*1505 j= 90300j

and for 7°c you need 7*90300j = 632100j, wich is answer D.

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Answer:

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Explanation:

we know that in a RL circuit with a resistance R, an inductance L and a battery of emf E, the current (i) will vary in following fashion

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⇒ $\frac{1}{2}=1-e^\frac{-2}{\frac{L}{R}}$

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Applying logarithm on both sides,

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⇒ $log(2)=\frac{2}{\frac{L}{R}}$

⇒ $\frac{L}{R}=\frac{2}{log2}$

Now substitute $i(t)=\frac{3}{4}imax=\frac{3E}{4R}$

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⇒ $\frac{3}{4}=1-e^\frac{-t}{\frac{L}{R}}$

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Applying logarithm on both sides,

⇒ $log(\frac{1}{4})=\frac{-t}{\frac{L}{R}}$

⇒ $log(4)=\frac{t}{\frac{L}{R}}$

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now subs. $\frac{L}{R}=\frac{2}{log2}$

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3 years ago

The kinetic friction force between a 60.0-kg object and a horizontal surface is 50.0 N. If the initial speed of the object is 25

Vikki [24]

Answer:

375 m.

Explanation:

From the question,

Work done by the frictional force = Kinetic energy of the object

F×d = 1/2m(v²-u²)..................... Equation 1

Where F = Force of friction, d = distance it slide before coming to rest, m = mass of the object, u = initial speed of the object, v = final speed of the object.

Make d the subject of the equation.

d = 1/2m(v²-u²)/F.................. Equation 2

Given: m = 60.0 kg, v = 0 m/s(coming to rest), u = 25 m/s, F = -50 N.

Note: If is negative because it tends to oppose the motion of the object.

Substitute into equation 2

d = 1/2(60)(0²-25²)/-50

d = 30(-625)/-50

d = -18750/-50

d = 375 m.

Hence the it will slide before coming to rest = 375 m

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3 years ago

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