This is due to the fact that below 4°c, water behaves differently than other substances and decreases in density as its temperature drops further.
Answer:

According to the guideline for kilometers, every three seconds between a lightning strike and the subsequent thunder indicates the distance to the flash in kilometers.
Explanation:
To calculate the speed of sound in meters per second, we need to utilize certain conversion factors. One mile corresponds to 5 seconds after witnessing the lightning. Furthermore, 1 mile comprises 5280 feet, and 1 foot is equivalent to 0.3048 meters. This information is sufficient to solve the issue. The conversion ratios can be set up like this:

Observe how the ratios are organized such that the units cancel out during calculations. One ratio has miles in the numerator while the other has them in the denominator, leading to cancellation. The same applies to the feet.
The question requires us to provide the answer to one significant figure, resulting in the speed of sound rounding to 300m/s.
For the second part, we will again utilize conversions. This time we will set our ratios in reverse and realize that there are 1000 meters in 1 kilometer, leading us to:

This signifies that for every 3.11 seconds, the distance to the lightning strike is 1 kilometer. Since this is a fabric of general knowledge, we round to the nearest whole number for simplicity, establishing the guideline:
According to the rule for kilometers, every three seconds between a lightning flash and the following thunder gives the distance to the flash in kilometers.
Answer:
Height (h) = 17 m
Velocity (v) = 18.6 m/s
Explanation: This problem can be solved using kinematic motion equations.
Given Data
Initial velocity (u) = 0
Acceleration (a) = g
Time (t) = 1.9 seconds
First, we calculate the height.

Then, we find the final velocity

The acceleration graph is a linear representation described by y=9.8, as it remains constant:
The velocity graph can be represented by y=9.8x (where y signifies velocity and x indicates time):
The displacement graph can be described as y=4.9x^2 (with x as time and y as displacement):
These graphs apply exclusively from x=0 to x=1.9, so disregard other sections of the graphs.
Answer:
Explanation:
Let T represent the tension in the swing.
At the peak 
where v denotes the velocity needed to maintain the circular motion.
r equals the distance from the rotation point to the center of the ball, which is L+\frac{d}{2} (with d being the ball's diameter).
The threshold velocity can be expressed as 
To determine the velocity at the bottom, we can use energy conservation principles at both the top and bottom positions.
At the top 
Energy at the bottom 
By comparing the two states using conservation of energy, we find 



We will utilize Wien's displacement law, given by the equation λ T = b, where λ represents the wavelength of emitted light from a heated object at maximum. By substituting the provided temperature and constant b into the equation, we find λ for various temperatures: at 500 K, λ = 5.796 μm or 5796 nm; at 1050 K, λ = 2760 nm; at 1800 K, λ = 1610 nm; and at 2500 K, λ = 1159.2 nm. The visible light spectrum starts at 740 nm, suggesting that at 2500 K, some visible red light may emerge as its calculated peak wavelength is within the visible range.