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Maurinko [17]
2 years ago
7

A student is standing 8 m from a roaring truck engine that is measured at 100 dB. The student moves 4 m closer to the engine. Wh

at is the measured loudness at the new distance?
Physics
2 answers:
mr_godi [17]2 years ago
7 0

The answer is 400 dB.

Evgen [1.6K]2 years ago
6 0
The loudness or sound intensity of the roaring truck engine is inversely proportional to the square of the distance. it follows the law of squares that is 
r1^2 / r2^2 = L2/L1
8^2 / 4^2 = L2 / 100 dB
L2 =  400 dB

The answer to this problem is 400 dB increased frim 100 dB.
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A brick of mass 2.0kg is at rest. It falls to the ground through a
Lisa [10]

Answer:

I may not have the answer so i'll just give up some hints.

Multiply the time by the acceleration due to gravity to find the velocity when the object hits the ground. If it takes 9.9 seconds for the object to hit the ground, its velocity is (1.01 s)*(9.8 m/s^2), or 9.9 m/s. Choose how long the object is falling. In this example, we will use the time of 8 seconds. Calculate the final free fall speed (just before hitting the ground) with the formula v = v₀ + gt = 0 + 9.80665 * 8 = 78.45 m/s . Find the free fall distance using the equation s = (1/2)gt² = 0.5 * 9.80665 * 8² = 313.8 m .h = 0.5 * 9.8 * (1.5)^2 = 11m. b. V = gt = 9.8 * 1.5 = 14.7m/s. A feather and brick dropped together. Air resistance causes the feather to fall more slowly. If a feather and a brick were dropped together in a vacuum—that is, an area from which all air has been removed—they would fall at the same rate, and hit the ground at the same time.When an object's point is taller the thing that is going down it will go faster than when the point is lower. EXAMPLE: The object is the tennis ball if you drop it down the higher hill it will be faster than if you drop it down a shorter hill. In other words, if two objects are the same size but one is heavier, the heavier one has greater density than the lighter object. Therefore, when both objects are dropped from the same height and at the same time, the heavier object should hit the ground before the lighter one.

I hope my little bit (big you may say) hint help you with your question.

5 0
2 years ago
If a small number of tree frogs migrate to a mat of vegetation that is already home to an established population of tree frogs a
Bingel [31]

Answer:

D

Explanation:

Gene flow is the transfer of genetic variation from one population to another

5 0
3 years ago
A 1,650 kg SUV comes uniformly to a stop. If the vehicle is accelerating at -1.3 m/s^2,
lions [1.4K]

Answer:b

Explanation:

4 0
3 years ago
Two +1 C charges are separated by 30000 m, what is the magnitude of<br> the force?
Kipish [7]

Answer:

<em>The magnitude of the force is 10 N</em>

Explanation:

<u>Coulomb's Law</u>

The electrostatic force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between the two objects.

Written as a formula:

\displaystyle F=k\frac{q_1q_2}{d^2}

Where:

k=9\cdot 10^9\ N.m^2/c^2

q1, q2 = the objects' charge

d= The distance between the objects

We have two identical charges of q1=q2=1 c separated by d=30000 m, thus the magnitude of the force is:

\displaystyle F=9\cdot 10^9\frac{1*1}{30000^2}

\displaystyle F=9\cdot 10^9\frac{1*1}{30000^2}

F = 10 N

The magnitude of the force is 10 N

7 0
2 years ago
A roller coaster car may be approximated by a block of mass m. Thecar, which starts from rest, is released at a height h above t
elena55 [62]

Answer:

The first part can be solved via conservation of energy.

mgh = mg2R + K\\K = mg(h-2R)

For the second part,

the free body diagram of the car should be as follows:

- weight in the downwards direction

- normal force of the track to the car in the downwards direction

The total force should be equal to the centripetal force by Newton's Second Law.

F = ma = \frac{mv^2}{R}\\mg + N = \frac{mv^2}{R}

where N = 0 because we are looking for the case where the car loses contact.

mg = \frac{mv^2}{R}\\v^2 = gR\\v = \sqrt{gR}

Now we know the minimum velocity that the car should have. Using the energy conservation found in the first part, we can calculate the minimum height.

mgh = mg2R + \frac{1}{2}mv^2\\mgh = mg2R + \frac{1}{2}m(gR)\\gh = g2R + \frac{1}{2}gR\\h = 2R + \frac{R}{2}\\h = \frac{5R}{2}

Explanation:

The point that might confuse you in this question is the direction of the normal force at the top of the loop.

We usually use the normal force opposite to the weight. However, normal force is the force that the road exerts on us. Imagine that the car goes through the loop very very fast. Its tires will feel a great amount of normal force, if its velocity is quite high. By the same logic, if its velocity is too low, it might not feel a normal force at all, which means losing contact with the track.

7 0
2 years ago
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