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3 years ago

Assuming the speed of sound is 340 m/s, what is the most likely speed of the jet shown below?

Physics

1 answer:

inysia [295]3 years ago

7 0

Well we know it has to be greater than 300,000 km/s since we can't see it.

We can't calculate it any closer than that using the given information.

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Two workers are sliding 300 kg crate across the floor. One worker pushes forward on the crate with a force of 400 N while the ot

almond37 [142]

Answer:

The kinetic coefficient of friction of the crate is 0.235.

Explanation:

As a first step, we need to construct a free body diagram for the crate, which is included below as attachment. Let supposed that forces exerted on the crate by both workers are in the positive direction. According to the Newton's First Law, a body is unable to change its state of motion when it is at rest or moves uniformly (at constant velocity). In consequence, magnitud of friction force must be equal to the sum of the two external forces. The equations of equilibrium of the crate are:

$\Sigma F_{x} = P+T-\mu_{k}\cdot N = 0$ (Ec. 1)

$\Sigma F_{y} = N - W = 0$ (Ec. 2)

Where:

$P$ - Pushing force, measured in newtons.

$T$ - Tension, measured in newtons.

$\mu_{k}$ - Coefficient of kinetic friction, dimensionless.

$N$ - Normal force, measured in newtons.

$W$ - Weight of the crate, measured in newtons.

The system of equations is now reduced by algebraic means:

$P+T -\mu_{k}\cdot W = 0$

And we finally clear the coefficient of kinetic friction and apply the definition of weight:

$\mu_{k} =\frac{P+T}{m\cdot g}$

If we know that $P = 400\,N$ , $T = 290\,N$ , $m = 300\,kg$ and $g = 9.807\,\frac{m}{s^{2}}$ , then:

$\mu_{k} = \frac{400\,N+290\,N}{(300\,kg)\cdot \left(9.807\,\frac{m}{s^{2}} \right)}$

$\mu_{k} = 0.235$

The kinetic coefficient of friction of the crate is 0.235.

5 0

3 years ago

A doppler effect occurs when a source of sound moves. True or False

Shtirlitz [24]

<h2>Answer: True </h2>

The <u>Doppler effect</u> refers to the change in a wave perceived frequency when the emitter of the waves, and the receiver (or observer in the case of light) move relative to each other.

In other words, it is the variation of the frequency of a wave due to the relative movement of the source of the wave with respect to its receiver.

It should be noted that this effect bears its name in honor of the Austrian physicist <u>Christian Andreas Doppler</u>, who in 1842 proposed the existence of this effect for the case of light in the stars. Another important aspect is that the effect occurs in all waves (including light and sound). However, it is more noticeable to humans with sound waves.

4 0

3 years ago

Which sentence uses the correct form of the verb choose?

MrRa [10]

Answer:

The answer is B

Explanation:

It's past tense and dad is singular

4 0

3 years ago

Read 2 more answers

How much does the Earth weigh? Why does the moon appear in the daytime?

ch4aika [34]

Answer:

moon disappear because of the rotation

7 0

3 years ago

How can Newton's laws be applied to protect a smartphone screen during a collision?

Sonja [21]

smartphones break due to forces acting on the material.

force causes material to deform.

material is often brittle and cracks due to a limit on hardness / electricity in screens.

newton's 2nd law states

force = DV / DT

to help phones we must slow down change in momentum to reduce the force

thus we must use some form of damping in the form of a case .

the case is typically able to deform and rubber is elastic converting the kinetic energy to heat as it deforms instead of transferring it through the screen.

therefore the change in velocity occurs over a longer time. therefore the impulse decreases

7 0

3 years ago