Answer:
iv) It is 9x bigger than before
Explanation:
As the amplitudes of the new speakers add directly with the original one, taking into account the phase that they have, the composed amplitude of the sound wave is as follows:
At = A + 4A -2A = 3 A
The intensity of the wave, assuming it propagates evenly in all directions, is constant at a given distance from the source, and can be expressed as follows:
I = P/A
where P= Power of the wave source, A= Area (for a point source, is equal to the surface area of a sphere of radius r, where is r is the distance to the source along a straight line)
For a sinusoidal wave, the power is proportional to the square of the amplitude, so the intensity is proportional to the square of the amplitude also.
If the amplitude changes increasing three times, the change in intensity will be proportional to the square of the change in amplitude, i.e., it will be 9 times bigger.
So, the statement iv) is the right one.
Answer:
She covers the distance is 12 km.
The magnitude of displacement is 8.6 km.
The direction of her displacement is north east.
Explanation:
Given that,
Christina drives his moped 7 kilometers North and stop for lunch and then drive 5 km east.
We need to calculate the total distance
Using formula of distance
![d=d_{1}+d_{2}](https://tex.z-dn.net/?f=d%3Dd_%7B1%7D%2Bd_%7B2%7D)
Put the value into the formula
![d=7+5](https://tex.z-dn.net/?f=d%3D7%2B5)
![d=12\ km](https://tex.z-dn.net/?f=d%3D12%5C%20km)
We need to calculate the magnitude of displacement
Using formula of displacement
![D=xi+yj](https://tex.z-dn.net/?f=D%3Dxi%2Byj)
![D=5i+7j](https://tex.z-dn.net/?f=D%3D5i%2B7j)
![D=\sqrt{5^2+7^2}](https://tex.z-dn.net/?f=D%3D%5Csqrt%7B5%5E2%2B7%5E2%7D)
![D= 8.6\ km](https://tex.z-dn.net/?f=D%3D%208.6%5C%20km)
The direction of her displacement is north east.
Hence, She covers the distance is 12 km.
The magnitude of displacement is 8.6 km.
The direction of her displacement is north east.
The average force on the ball by the racket is 98 N. The correct option is the third option - 98 N
From the question, we are to determine the average force on the ball by the racket.
From the formula,
![F = \frac{mv}{t}](https://tex.z-dn.net/?f=F%20%3D%20%5Cfrac%7Bmv%7D%7Bt%7D)
Where F is the force
m is the mass
v is the velocity
and t is the time
From the given information
m = 0.07 kg
v = 56 m/s
t = 0.04 s
Putting the parameters into the formula,
we get
![F = \frac{0.07 \times 56}{0.04}](https://tex.z-dn.net/?f=F%20%3D%20%5Cfrac%7B0.07%20%5Ctimes%2056%7D%7B0.04%7D)
![F = \frac{3.92}{0.04}](https://tex.z-dn.net/?f=F%20%3D%20%5Cfrac%7B3.92%7D%7B0.04%7D)
F = 98 N
Hence, the average force on the ball by the racket is 98 N. The correct option is the third option - 98 N
Learn more on calculating force exerted on an object here: brainly.com/question/13590154