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3 years ago

Select the correct answer

Physics

1 answer:

DiKsa [7]3 years ago

7 0

Answer:

C or 3

Explanation:

A: no they are called sources of sound. A is incorrect.

B: It does. Many people attest to this. But this is not a property of physics.

C: A media is required is the correct answer.

D: Dogs might. In general we don't.

I would pick C

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The energy efficiency of a car is approximately 20%. If you put 10 gallons of gas into the car, how many gallons are “wasted”?

podryga [215]

First, you find what 20% of 10 gallons of gas would be. This will show how many gallons the car actually uses.
10 gallons x 20% =
10 x 0.20 =
2 gallons used

Then you subtract that number from the total 10 gallons to get how many gallons of gas would be wasted.
10 gallons - 2 gallons =
8 gallons of gas wasted

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3 years ago

Why can work be thought of as the transfer of energy? Please help it's physics

deff fn [24]

That is because work requires energy. According to the law of conservation of energy, it cannot be created or destroyed. When doing work, energy change forms and gets transferred to the object until it is released.
for example, when you lift up an object and place it on a higher elevation, you transferred energy to it and gave it potential energy. The potential energy is transformed into kinetic energy when the object falls down, and if it hits a surface, the energy will scatter, vibrating the areas around it and producing sound.
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3 years ago

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Please help <br>Newton second law of motion is F =ma <br>

mamaluj [8]

Answer: ma is the formula of Newton's Second Law of Motion. Newton's Second Law of Motion is defined as Force is equal to the rate of change of momentum. For a constant mass, force equals mass times acceleration.

Explanation: Newton's second law of motion is F = ma, or force is equal to mass times acceleration.

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3 years ago

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How does the work required to accelerate a particle from 10 m/s to 20 m/s compare to that required to accelerate it from 20 m/s

poizon [28]

To solve this problem we will apply the energy conservation theorem for which the work applied on a body must be equivalent to the kinetic energy of this (or vice versa) therefore

$W = \Delta KE$

$\Delta W = \frac{1}{2} (m)(v_f)^2 -\frac{1}{2} (m)(v_i)^2$

Here,

m = mass

$v_{f,i}$ = Velocity (Final and initial)

First case) When the particle goes from 10m/s to 20m/s

$\Delta W = \frac{1}{2} (m)(v_f)^2 -\frac{1}{2} (m)(v_i)^2$

$\Delta W = \frac{1}{2} (m)(20)^2 -\frac{1}{2} (m)(10)^2$

$W_1 = 150(m) J$

Second case) When the particle goes from 20m/s to 30m/s

$\Delta W = \frac{1}{2} (m)(v_f)^2 -\frac{1}{2} (m)(v_i)^2$

$\Delta W = \frac{1}{2} (m)(30)^2 -\frac{1}{2} (m)(20)^2$

$W_1 = 250(m) J$

As the mass of the particle is the same, we conclude that more energy is required in the second case than in the first, therefore the correct answer is A.

5 0

3 years ago

A stone is dropped from the top a 45m hign building how fast will it moving when it reaches the ground? Ande what will its veloc

posledela

Answer:

29.7 m/s fast, velocity is 29.7 m/s

Explanation:

Applying,

v² = u²+2gs...................... Equation 1

Where v = final velocity, u = initial velocity, g = acceleration due to gravity, s = distance.

Given: u = 0 m/s (dropped from height), s = 45 m

Constant: g = 9.8 m/s²

Substitute these values into equation 1

v² = 0²+2×9.8×45

v² = 882

v = √(882)

v = 29.7 m/s.

Hence the stone will be moving 29.7 m/s fast and the velocity is also 29.7 m/s

7 0

3 years ago