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wel
3 years ago
8

Please i really need help! :/

Physics
2 answers:
valina [46]3 years ago
8 0
Answer: D

Explanation:
Let us examine the given actions to see which ones generate heat and sound energy from mechanical energy.

A) Stretching a string.
The mechanical stretching creates tension in the string, which is released when the tension is removed. The generation of thermal or sound energy is minimal or negligible.

B) Squeezing a sponge ball
The sponge ball experiences compressive loading. This generates minimal or no heat and sound energy.

C) Throwing a ball upwards in the air
Air friction generates minimal or no heat at low velocities. At low velocities the pressure waves are too small to generate sound.

D) Striking a hammer on a nail.
A tremendous amount of force is applied over a small area to generate very high stresses that are in the plastic zone. A high amount of thermal energy is generated and the localized disturbance of the air generates audible sound.
This is the correct situation.


Andru [333]3 years ago
8 0

Answer:

the answer is D, I took the test

Explanation:

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bearhunter [10]
Sure.
Can I use your answer to part-'a' ?

If the angular acceleration is actually 32 rev/min², than
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Check:

If the initial speed is zero and the final speed is 38.4 rpm,
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At an average speed of  19.2 rpm for 1.2 min,
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4 0
3 years ago
Read 2 more answers
Salmon often jump waterfalls to reach their
PilotLPTM [1.2K]

The minimum velocity of the Salmon jumping at the given angle is 12.3 m/s.

The given parameters;

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  • distance of the Salmon from the waterfall, s = 3.17 m
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The time of motion to fall from 0.432 m is calculated as;

h = v_0_y + \frac{1}{2} gt^2\\\\0.432 = 0 + (0.5\times 9.8)t^2\\\\0.432 = 4.9t^2\\\\t^2 = \frac{0.432}{4.9} \\\\t^2 = 0.088\\\\t = \sqrt{0.088} \\\\t = 0.3 \ s

The minimum velocity of the Salmon jumping at the given angle is calculated as;

X = v_0_x t\\\\3.17 = (v_0\times cos(30.8)) \times 0.3\\\\10.567 = v_0\times cos(30.8)\\\\v_0 = \frac{10.567}{cos(30.8)} \\\\v_0 = 12.3 \ m/s

Thus, the minimum velocity of the Salmon jumping at the given angle is 12.3 m/s.

Learn more here: brainly.com/question/20064545

8 0
2 years ago
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alisha [4.7K]

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5 0
3 years ago
Why is the same side of the Moon always visible from Earth?
son4ous [18]

Answer:

Explanation:

Answer

The true fact is that C is what happens in outer space.  Both rotations take 27.3 days.  

A: The exact opposite is true. It does rotate about it's axis.

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