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vlada-n [284]
3 years ago
6

A 90dB sound wave strikes an eardrum whose area is 5.0×10^-5m^2. How much energy is absorbed by the eardrum per second

Physics
1 answer:
MakcuM [25]3 years ago
6 0

-- The reference level for sound wave intensity is the threshold of human hearing, defined as  10⁻¹² W/m² .

-- This question is talking about a 90dB sound.  So its intensity is 10⁻³ W/m² .

-- The question tells us the size of the area that this sound is hitting.  So the power absorbed by that area is ...

Power = (intensity) x (area)

Power = (10⁻³ W/m²) x (5 x 10⁻⁵ m²)

Power = (10⁻³ x 5 x 10⁻⁵) W

<em>Power = 5 x 10⁻⁸ Watts</em>

(That's 5 x 10⁻⁸ Joules of energy per second.)

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A high diver dives into a swimming pool. His potential energy at the top is 10,000 J (relative to the surface of the pool). What
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Answer:

Kinetic energy of diver at 90% of the distance to the water is 9000 J

Explanation:

Let d is the distance between the position of the diver and surface of the pool.

Initially, the diver is at rest and only have potential energy which is equal to 10000 J.

As the diver dives towards the pool, its potential energy is converting into kinetic energy due to law of conservation of energy, as total energy of the system remains same.

Energy before diving = Energy during diving

(Potential Energy + Kinetic Energy) =  (Kinetic Energy +  Potential Energy)

When the diver reaches 90% of the distance to the water, its kinetic energy

is 90% to its initial potential energy, as its initial kinetic is zero,i.e.,

K.E. = \frac{90}{100}\times10000

K.E. = 9000 J

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3 years ago
Since all objects are ‘weightless’ for an astronaut in orbit, is it possible for astronauts to tell whether an object is heavy o
ivanzaharov [21]
W=gm
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3 years ago
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Before we dive into how electricity is used around the home it is worth putting household electricity use in perspective.

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If ball 4 has a mass of 2 kg and it is 5m high, what will be its gravitational potential energy? (g=10 N/kg) *
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Explanation:

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A three dimensional vector can be divided into three components: one along x-axis, one along y-axis and one along z-axis.

Hence, the vector parts that add up to the resultant are called components.

2. Answer: 5 miles.

The resultant distance along the straight line from the starting point to the end point would be the displacement.

The displacement would be equal to the magnitude of the hypotenuse formed in the right triangle.

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