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Levart [38]
3 years ago
10

A person wants to find the width of the lake by shouting and listening for the echo from the far side. If his echo returns after

2 seconds how wide is the lake? (Velocity of sound is 340 m/sec)
Physics
1 answer:
Ber [7]3 years ago
6 0

Answer:

<em>The width of the lake is 340 m</em>

Explanation:

<u>Constant Velocity Motion</u>

It occurs when an object travels the same distance every equal interval. For example, if it travels 5 m in one second, then 10 m in two seconds, etc., it has a constant velocity.

The speed of the sound is assumed as v=340 m/s and the person measures the time that a sound goes and comes from the edge of a lake as t=2 seconds. The distance it travels is:

d = v.t

d = 340 m/s * 2 s

d = 680 m

But that distance is twice the width of the lake, the real measured width is 680 m / 2 = 340 m

The width of the lake is 340 m

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Oksanka [162]

a) The speed of the wave will increase by a factor \sqrt{2}.

b) The speed of the wave will halve

c) The speed of the wave will double

Explanation:

a)

The speed of a standing wave on a string is given by

v=\sqrt{\frac{T}{m/L}}

where

T is the tension in the string

m is the mass of the string

L is the length of the string

In this part of the problem, the tension in the string is doubled, so that the new tension is

T' = 2T

Substituting into the equation, we find the new speed of the wave in the string:

v'=\sqrt{\frac{T'}{m/L}}=\sqrt{\frac{2T}{m/L}}=\sqrt{2}\sqrt{\frac{T}{m/L}}=\sqrt{2}v

So, the speed will increase by a factor \sqrt{2}.

b)

We can solve also this part by referring to the formula

v=\sqrt{\frac{T}{m/L}}

where

T is the tension

m is the mass

L is the length

In this case, the string mass is quadrupled, so the new mass is:

m' = 4m

Substituting into the equation, we find what happens to the speed of the wave:

v'=\sqrt{\frac{T}{m'/L}}=\sqrt{\frac{T}{4m/L}}=\frac{1}{\sqrt{4}}\sqrt{\frac{T}{m/L}}=\frac{1}{2}v

So, the speed of the wave will halve.

c)

Again, we can solve this part by referring to the same equation

v=\sqrt{\frac{T}{m/L}}

where

T is the tension

m is the mass

L is the length

In this case, the length of the string is quadrupled, so the new length is:

L' = 4L

Substituting into the equation, we find that the new speed is:

v'=\sqrt{\frac{T}{m/L'}}=\sqrt{\frac{T}{m/(4L)}}=\sqrt{4}\sqrt{\frac{T}{m/L}}=2v

So, the speed of the wave will  double.

Learn more about waves:

brainly.com/question/5354733

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3 0
4 years ago
The place you get your hair cut has two nearly parallel mirrors 6.5 m apart. As you sit in the chair, your head is 2.0 m from th
ASHA 777 [7]

Answer:

13 m

Explanation:

It is given that :

I got a haircut  sitting at a place having two parallel mirrors at a distance = 6.5 m apart

My head is at a distance of 2 m from the nearer mirror.

Now the light from the back of my head must go to (6.5 - 2) = 4.5 m to the back mirror.

Then it must go to 6.5 m to the front mirror and 2 m from the front mirror to my eyes.

So in order to see the back of my head, it will be = 6.5 + 2 + 4.5 = 13 m away.

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Brrunno [24]
The boys body will continue to move in a forward motion, the stairs an an will make the skateboard come to a complete stop because the force of the stairs is much greater, this makes in an unbalanced force. This is and example of inertia of motion.
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True or False A Safety Data Sheet (SDS) provides even more information on chemicals than a label.
Sonja [21]

A Safety Data Sheet (SDS) provides even more information on chemicals than a label: True.

<h3>What is a Safety Data Sheet (SDS)?</h3>

A Safety Data Sheet (SDS) can be defined as a text-based document (bulletin) that is developed to provide more information with respect to the chemical and physical properties of a chemical compound, substance or equipment such as:

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Additionally, a Safety Data Sheet (SDS) contains information on the potential health hazards and safety precautions for proper use, handling, storage and transportation of a chemical compound, substance or equipment.

In conclusion, we can deduce that a Safety Data Sheet (SDS) provides even more information on chemicals than a label, which only contains lesser information about a product.

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