Answer:
r = 2.63 m
Explanation:
To find the distance at which the sound level is 120dB, you first calculate the intensity of the sound. You use the following formula:
(1)
β: sound level = 120dB
I: intensity of the sound
Io: threshold of hearing = 10⁻12W/m^2
You solve the equation (1) for I and replace the values of all parameters:
Next, you use the following formula for the power of the sound with intensity I, and you solve for r:
r: distance at which the sound level is 120dB
P: power of the sound = 87W
I: intensity of the sound = 1W/m^2
You replace the values of I and P for calculating r:
The distance is at 2.63m from the source of the soundr = 2.63m
Answer:
The weight of an object would be less on the moon than on the earth
Explanation:
Thus, our object has mass m both on the surface of the Earth and on the surface of the Moon, but it will weigh much less on the surface of the Moon because the gravitational acceleration there is a factor of 6 less than at the surface of the Earth.
F_P + F_Q = M g
F_P = M g - F_Q
Torque, or moment of force:
∑ M_P = 0
∑ M_P = M g L - F_Q · 3 L
0 = M g L - 3 F_Q L / : L
0 = M g - 3 F_Q
3 F_Q = M g
F_Q = M g /3
Finally:
F_P = M g - M g/3
F_P = 4 M g / 3
Answer: D) subatomic, atomic, and nanometer-size systems.
Explanation: Quantum mechanics applies to subatomic, atomic, and nanometer-size systems.