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3 years ago

A child has an ear canal that is 1.3 cm long. Assume the speed of sound is v = 344 m/s.

Physics

1 answer:

kap26 [50]3 years ago

6 0

Answer:

The frequencies are $(f, f_1) = (6615.4 \ Hz , 19846.2\ Hz)$

Explanation:

From the question we are told that

The length of the ear canal is $l = 1.3 \ cm =\frac{1.3}{100} = 0.013 \ m$

The speed of sound is assumed to be $v_s = 344 \ m/s$

Now taking look at a typical ear canal we see that we assume it is a closed pipe

Now the fundamental harmonics for the pipe(ear canal) is mathematically represented as

$f = \frac{v_s}{4 * l }$

substituting values

$f = \frac{344}{4 * 0.013 }$

$f = 6615.4 \ Hz$

Also the the second harmonic for the pipe (ear canal) is mathematically represented as

$f_1 = \frac{3v_s}{4 * l}$

substituting values

$f_1 = \frac{3 * 344}{4 * 0.013}$

$f_1 = 19846.2 \ Hz$

Given that sound would be loudest in the pipe at the frequency, it implies that the child will have an increased audible sensitivity at this frequencies

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a 0.25 kg arrow is moving at 5 m/s and hits a 0.10 kg apple. The apple sticks to the arrow, and both move to the right together.

MatroZZZ [7]

Answer:

The arrow-apple combo will move with a velocity 3.6 m/s to the right.

Explanation:

Use the law of conservation of momentum to solve this problem. In this case the law can be written as follows:

$m_{arrow}v_{arrow}+m_{apple}\cdot 0= (m_{arrow}+m_{apple})v_{both}$

from which the desired velocity can be isolated:

$\frac{m_{arrow}v_{arrow}}{m_{arrow}+m_{apple}}= v_{both}\\v_{both} = \frac{0.25kg\cdot 5\frac{m}{s}}{0.35kg}=3.6\frac{m}{s}$

The arrow-apple combo will move with a velocity 3.6 m/s to the right.

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3 years ago

The floor of a railroad flatcar is loaded with loose crates having a coefficient of static friction of 0.420 with the floor. If

bonufazy [111]

Answer:

The distance is $s= 30.3 \ m$

Explanation:

From the question we are told that

The coefficient of static friction is $\mu_s = 0.42$

The initial speed of the train is $u = 57 \ km /hr = 15.8 \ m/s$

For the crate not to slide the friction force must be equal to the force acting on the train i.e

$-F_f = F$

The negative sign shows that the two forces are acting in opposite direction

=> $mg * \mu_s = ma$

=> $-g * \mu_s = a$

=> $a = -9.8 * 0.420$

=> $a = -4.116 m/s^2$

From equation of motion

$v^2 = u^2 + 2as$

Here v = 0 m/s since it came to a stop

=> $s= \frac{v^2 - u^2 }{ 2 a}$

=> $s= \frac{0 -(15.8)^2 }{ - 2 * 4.116}$

=> $s= 30.3 \ m$

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3 years ago

All objects emit what radiation

Eduardwww [97]

If an object is not at Absolute Zero, then it is
absorbing and radiating thermal (heat) energy.

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3 years ago

According to Newton’s law of universal gravitation, which statements are true?

andreyandreev [35.5K]

Before we solve this, we should know this fact:

According to Newton's Law of Gravitation, the force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. The force acts along the line joining the centres of the two objects. It can be shown by this:

$F ∝ \frac{Mm}{ {d}^{2} }$

Now, let us check all the options.

A. As we move to higher altitudes, the force of gravity on us decreases.

This statement is true.

The force of gravity is inversely proportional to the square of distance from the centre of the earth. If, we go up the surface of the earth, the distance from the centre of the earth increases and hence the value of force of gravity decrease. So, force of gravity decreases with altitude.

B. As we move to higher altitudes, the force of gravity on us increases.

This statement is false.

We have already got the result in option A. that the force of gravity decreases with altitude. It never increases with altitude.

C. As we gain mass, the force of gravity on us decreases.

This statement is false.

The force of gravity is directly proportional to the product of the masses. So, if increase our mass, then the force of gravity will also increase and if we decrease our mass, then the force of gravity decreases.

D. As we gain mass, the force of gravity on us increases.

This statement is true.

As mentioned earlier in option C., the force of gravity is directly proportional to the product of the masses of the earth and another object. So, as we gain mass, the force of gravity on us increases.

E. As we move faster, the force of gravity on us increases.

This statement is true.

Here, we have to consider a different formula. According to Newton's Second Law,

F = ma, where F is the force, m is the mass and a is the acceleration.

In other words,

F ∝ a, i.e., force is directly proportional to acceleration.

We know, acceleration is the rate of change of velocity of an body within a time period.

So, if speed is increased, then acceleration will also be greater, which results in the increase of force. So, as we move faster, the force of gravity on us increases.

Answers:

A: As we move to higher altitudes, the force of gravity on us decreases.

D: As we gain mass, the force of gravity on us increases.

E: As we move faster, the force of gravity on us increases.

Hope you could understand.

If you have any query, feel free to ask.

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2 years ago

Which represents the net force

ipn [44]

Answer:

The net force is 500N downwards

Explanation:

When Haley is trying to pull an object upward. The below forces are acting on the object.

Fp = 5500N

Fg = 6000N

because the force of gravity is more than the force of the pull.

Fnet = Fg - Fp = 6000N - 5500N = 500N

And, the direction of the resultant force is the direction of the larger force.

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3 years ago