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Greeley [361]
3 years ago
11

Why do people tend to cup their hands around listeners' ears when whispering to them? A) A cupped hand makes the sound echo so t

he listener can hear more clearly. B) The ear cannot absorb sound waves produced by a whisper without a cupped hand. C) Solid objects, such as a cupped hand, can direct sound waves into the ear of the listener. D) Sound waves from a whisper are short; they will not reach the listener's ear unless guided by a hand. Eliminate
Physics
2 answers:
WITCHER [35]3 years ago
6 0
C. Hope this helps you!
pashok25 [27]3 years ago
4 0

Answer: Option (C) is the correct answer.

Explanation:

In solids, sound travels faster because in solids the molecules are much more closer to each other as compared to liquids and gases.

Hence, distance between molecules is the minimum in solids and sound passes from one molecule to another easily.

Thus, we can conclude that people tend to cup their hands around listeners' ears when whispering to them because solid objects, such as a cupped hand, can direct sound waves into the ear of the listener.  

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A boy reaches out of a window and tosses a ball straight up with a speed of 10 m/s. The ball is 20 m above the ground as he rele
kirill115 [55]

Explanation:

It is given that,

Speed of the ball, v = 10 m/s

Initial position of ball above ground, h = 20 m

(a) Let H is the maximum height reached by the ball. It can be calculated using the conservation of energy as :

\dfrac{1}{2}mv^2=mgh'            

h'=\dfrac{v^2}{2g}

h'=\dfrac{(10)^2}{2\times 9.8}

h' = 5.1 m

The maximum height above ground,

H = 5.1 + 20

H = 25.1 meters

So, the maximum height reached by the ball is 25.1 meters.

(b) The ball's speed as it passes the window on its way down is same as the initial speed i.e. 10 m/s.

Hence, this is the required solution.                              

6 0
3 years ago
The 45-g arrow is launched so that it hits and embeds in a 1.40 kg block. The block hangs from strings. After the arrow joins th
worty [1.4K]

Question: How fast was the arrow moving before it joined the block?

Answer:

The arrow was moving at 15.9 m/s.

Explanation:

The law of conservation of energy says that the kinetic energy of the arrow must be converted into the potential energy of the block and arrow after it they join:

\dfrac{1}{2}m_av^2 = (m_b+m_a)\Delta Hg

where m_a is the mass of the arrow, m_b is the mass of the block, \Delta H of the change in height of the block after the collision, and v is the velocity of the arrow before it hit the block.

Solving for the velocity v, we get:

$v = \sqrt{\frac{2(m_b+m_a)\Delta Hg}{m_a} } $

and we put in the numerical values

m_a = 0.045kg,

m_b = 1.40kg,

\Delta H = 0.4m,

g= 9.8m/s^2

and simplify to get:

\boxed{ v= 15.9m/s}

The arrow was moving at 15.9 m/s

6 0
3 years ago
Whats the Independent and Dependent Variables
astra-53 [7]
The independent variable is the type of fuel used and the dependent variable is the speed of the race car. The independent variable could be changed through the experimental process to see its relation with the dependent variable<span>. The dependent variable is the result of the independent variable changes.</span>
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3 years ago
Vitamins and iron are nutrients that provide energy to the human body.<br> A true<br> B false
SIZIF [17.4K]
I think it is A. but then you can also produce your own energy
4 0
3 years ago
A 4 V power source is connected in parallel to four resistors: 1, 2, 2, and 3. Find the total current.
Keith_Richards [23]

Answer:

Explanation:

Equivalent resistance is 1 / ((1/1) + (1/2) + (1/2) + (1/3)) = 3/7 Ω

I = V/R = 4(7/3) = 28/3 = 9.3 A    

4 0
2 years ago
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