Answer: 2.72 metres
Explanation:
Given that:
frequency of sound F = 123 Hz. wavelength of sound in the air = ?
speed of sound in air V = 334 m/s
Recall that wavelength is the distance covered by the wave after one complete cycle. It is measured in metres, and represented by the symbol λ.
So, apply V = F λ
λ = V /F
λ = 334m/s / 123Hz
λ = 2.72m
Thus, the wavelength of this sound in the air is 2.72 metres
Answer:

Explanation:
The strength of an electric field E produced by a single charge Q at a distance d from it is given by the formula:
, where K represents the Coulomb constant.
Since the electric field E is derived from the Coulomb Force per unit charge using a positive test charge, the field's units will be in units of Newtons/Coulomb, and be the formula for the Coulomb electric force between to charges (Q1 and Q2),

but modified with only one charge showing in the numerator of the expression.
Answer:
v=5.86 m/s
Explanation:
Given that,
Length of the string, l = 0.8 m
Maximum tension tolerated by the string, F = 15 N
Mass of the ball, m = 0.35 kg
We need to find the maximum speed the ball can have at the top of the circle. The ball is moving under the action of the centripetal force. The length of the string will be the radius of the circular path. The centripetal force is given by the relation as follows :

v is the maximum speed

Hence, the maximum speed of the ball is 5.86 m/s.
Answer:
-4500 N
Source: Brainly
The police officer must be angry 0_0
Answer:

The rule for kilometers is that every three seconds between a lightning flash and the following thunder gives the distance to the flash in kilometers.
Explanation:
In order to use the rule of thumb to find the speed of sound in meters per second, we need to use some conversion ratios. We know there is 1 mile per every 5 seconds after the lightning is seen. We also know that there are 5280ft in 1 mile and we also know that there are 0.3048m in 1ft. This is enough information to solve this problem. We set our conversion ratios like this:

notice how the ratios were written in such a way that the units got cancelled when calculating them. Notice that in one ratio the miles were on the numerator of the fraction while on the other they were on the denominator, which allows us to cancel them. The same happened with the feet.
The problem asks us to express the answer to one significant figure so the speed of sound rounds to 300m/s.
For the second part of the problem we need to use conversions again. This time we will write our ratios backwards and take into account that there are 1000m to 1 km, so we get:

This means that for every 3.11s there will be a distance of 1km from the place where the lightning stroke. Since this is a rule of thumb, we round to the nearest integer for the calculations to be made easily, so the rule goes like this:
The rule for kilometers is that every three seconds between a lightning flash and the following thunder gives the distance to the flash in kilometers.