I was doing some revision of the thermal stuff and I decided to have a go at the question in the purple box in the attached link but I don't see how part (a) can be worked out if we don't know any time values, can the time values be work out using the graph?
If you see lightning then start counting until you hear the thunder, it's quite easy to calculate. Lets say you count 10 seconds between the two. You know this corresponds to around 2 miles. To convert from miles to km, we multiply by roughly 1.6, and a further 1000 to meters.
I was doing some revision of the thermal stuff and I decided to have a go at the question in the purple box in the attached link but I don't see how part (a) can be worked out if we don't know any time values, can the time values be work out using the graph?
It says the distance in miles can be calculated by counting the seconds from the flash (instant the thunder is generated) until it can be heard and dividing that time in seconds by five to give an answer in miles.
Speed = distance / time = 1 mile / 5 seconds
1 mile = 1600 metres approx.
So approximate speed of sound in air using this method is 1600/5 = 320m/s