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.
Answer:
Part a)

Part b)



Part c)



Explanation:
Part a)
As we know that charge density is the ratio of total charge and total volume
So here the volume of the charge ball is given as



now the charge density of the ball is given as

Part b)
Now the charge enclosed by the surface is given as

at radius of 5 cm


at radius of 10 cm


at radius of 20 cm

Part c)
As we know that electric field is given as

so we have electric field at r = 5 cm


electric field at r = 10 cm


electric field at r = 20 cm


Answer:
may be upside down alphabet :"T"
Explanation:
When you touch an object and heat flows OUT of it, INTO your finger, you say the object feels hot.
When you touch an object and heat flows INTO it, OUT of your finger, you say the object feels cold.
If the object has the same temperature as your finger ... <em>around the mid-90s</em> ... then no heat flows in or out of your finger when you touch the object, and the object doesn't feel hot or cold.
11.86 years. Usually memorized as "12 years".