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3 years ago

9

Which of the following is true about conduction? Question 2 options: It is heat transfer through direct contact It can only occu

r in a liquid It is heat transfer in currents through a liquid It is heat transfer as a form of light

1 answer:

kramer3 years ago

3 0

Answer:

through direct contact

Explanation:

took the test!

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If you stay on earth while a friend races off in a rocket at a speed close to the speed of light, then according to special rela

Natasha_Volkova [10]

Answer:

D-slower than the clock on the rocket.

Explanation:

In 1905, Albert Einstein devised the theory that states that laws of physics are the same for all non-accelerating observers, and that the speed of light in a vacuum was independent of the motion of all observers. This conclusion is generally referred to as the theory of special relativity. It defined an entirely new framework for physics as well as proposed new concepts of space and time.

He discovered that space and time were interwoven into a single continuum known as space-time. According to him, events that occur at the same time for one observer could occur at different times for another, hence the answer.

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3 years ago

A frame hanging on a wall is held by two cables. The tension in each cable is 30 N, and the cables make an angle of 45° with the

Dimas [21]

Answer: option D) 42.4 N

The weight of the frame is balanced by the vertical component of tension.

W = T sin θ + T sin θ = 2 T sin θ

The tension in each cable is T = 30 N

Angle made by the cables with the horizontal, θ = 45°

⇒ W = 2×30 N × sin 45° = 2 × 30 N × 0.707 = 42.4 N

Hence, the weight of the frame is 42.4 N. Correct option is D.

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3 years ago

A large refrigerator (mass 80kg) sits at rest inside a house. The homeowner wants to move the refrigerator across the room, so s

Liono4ka [1.6K]

Answer:

400 N

Explanation:

By the law of friction,

$F=\mu R$

$F$ is the maximum frictional force, $\mu$ is the coefficient of friction and $R$ is the reaction on the refrigerator. On a horizontal surface, the reaction is equal to the weight of the refrigerator.

$R=mg$

$F=\mu mg$

While not moving, the fricition on the refrigerator is static friction. So, $\mu=0.65$

$F=0.65 \times80\times9.8=509.6 \text{ N}$

This is the maximum frictional force and is more than the applied horizontal force of 400 N. Frictional force cannot be more than the applied force, else it would actually pull the refrigerator backwards (a strange thing, if it were to happen). It is equal to the extent of the applied force because the applied force is not enough to overcome the maximum.

Hence the frictional force is 400 N.

PS: Note that we do not use the coefficient of kinetic friction because applied force could not overcome the static friction.

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3 years ago

Arunner starts from rest and accelerates uniformly to a speed of 8.0 meters per

VladimirAG [237]

Answer:

2.0 m/s/s

Explanation:

The acceleration of an object is the rate of change of velocity of the object.

Mathematically, it is given by:

$a=\frac{v-u}{t}$

where

u is the initial velocity

v is the final velocity

t is the time taken for the velocity to change from u to v

Acceleration is a vector, so it has both a magnitude and a direction.

For the runner in this problem, we have:

u = 0 is the initial velocity (he starts from rest)

v = 8.0 m/s is the final velocity

t = 4.0 s is the time taken

Substituting, we find

$a=\frac{8.0-0}{4.0}=2.0 m/s^2$

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3 years ago

is it possible to breed a black haired long tailed retriever? If so, what percentage is possible? PLEASE answer the corrects ans

Pachacha [2.7K]

Answer: it can be considered a genetic mutation with a history of a Golden Retriever in their blood but it is very rare. and there our some black retrievers you can buy too. i hope i helped

Explanation:

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1 year ago

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