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3 years ago

ANswer the question and give example: Can friction ever perform positive work?

2 answers:

4 0

Yes. Think of block sitting on top of a bigger block. If the bottom block moves, it will drag the top block with it. Since the force of friction on the small block and its displacement are in the same direction, the "work" is positive. The static friction is a passive force, It is not a source of energy; it transmits the force placed on the bottom block. (And the "work" done by the friction on the bottom block is exactly the negative of the work done on the top block.)

quester [9]3 years ago

3 0

It do both Positive and Negative work.
If we have to stop some object then friction does a positive work.
For Example: to stop a car , necassary friction is required between the tyres of car and road to stop a car .

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Which is best supported by the data in the chart?

bija089 [108]

Answer:

Option C: Current X has a lower potential difference than Current Y.

Explanation:

The chart above only shows the potential difference of difference current.

A careful observation of the chart shows that Current X has a lower potential difference than Current Y.

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2 years ago

Two astronauts, each having a mass of 74.3 kg are connected by a 13.1 m rope of negligible mass. They are isolated in space, orb

murzikaleks [220]

Answer:

L = 5076.5 kg m² / s

Explanation:

The angular momentum of a particle is given by

L = r xp

L = r m v sin θ

the bold are vectors, where the angle is between the position vector and the velocity, in this case it is 90º therefore the sine is 1

as we have two bodies

L = 2 r m v

let's find the distance from the center of mass, let's place a reference frame on one of the masses

$x_{cm}$ = $\frac{1}{M} \sum x_{i} m_{i}$ i

x_{cm} = $\frac{1}{m+m} ( 0 + l m)$

x_{cm} = $\frac{1}{2m} lm$

x_{cm} = $\frac{1}{2}$

x_{cm} = 13.1 / 2 = 6.05 m

let's calculate

L = 2 6.05 74.3 5.65

L = 5076.5 kg m² / s

4 0

2 years ago

Read 2 more answers

a cyclist coasting down a 5.0 ◦ incline at a constant speed of 6.0 km/h because of air resistance. If the total mass of the bicy

Dvinal [7]

Answer:

$F_{net}= 85.41\ N$

Explanation:

mass of the bicycle + cyclist = 50 kg

constant speed = 6 km/h

a cyclist coasting down a 5.0° incline

the downward velocity is constant, so net acceleration must be zero

the air drag must be equal to gravitational force downward along the ramp

$F_a = mg sin \theta$

now for upward motion

$F_{net} = mg sin \theta + air\ drag$

$F_{net} = mg sin \theta + mg sin \theta$

$F_{net} = 2 mg sin \theta$

$F_{net} = 2\times 50 \times 9.8 sin 5^0$

$F_{net}= 85.41\ N$

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3 years ago

Why freezer is made in the upper part of refrigrator

svp [43]

<h2>Question</h2>

why freezer is made in the upper part of refrigrator

<h2>✒ Answer</h2>

the cold air produced from it is denser than the warmer air in the bottom

<h3>Explaination</h3>

Freezer is normally provided at the top of the refrigerator, because density of the cold air is high compared to the hot air. In a refrigerator the air contacts with the cooling coil and gets cooling.Because of the high density the cold air gets down and the warm air/hot air moves upward and gets cooling from the cooling coil/evaporator coil. This process is repeated. If the Freezer is provided at the bottom place of the refrigerator, the cold air can't to move full area of the refrigerator. So the freezer is normally provided at the top at the refrigerator

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