1. a student had no thermometer, so in order to measure the temperature, she resourcefully used the following procedure. she accurately measured a distance of 100 m from a wall, then struck two stones together so that each new strike coincided with the echo from the previous strike. the student found that the time to make 150 strikes was 92s. to the nearest degree, what was the air temperature? 2. a lightning flash is seen 10s before the rumble of the thunder is heard. find the distance to the lightning flash if the air temperature is 2o c degrees. ( speed of light: c=3*10^8m/s)

1. You can solve this problem if you know the speed of sound in air as a function of its temperature.

The formula to find the speed of sound in air is as follows:

v = 331m/s + 0.6m/s/C * T

v is the speed of sound and T is the temperature of the air. One thing to keep in mind is that this formula finds the average speed of sound for any given temperature. The speed of sound is also affected by other factors such as humidity and air pressure.

Is it (1) the time from the first strike to the 150th strike? Or (2) the time from the first strike to the echo of the 150th strike?

If (1), the sound travelled 2 x 149 x 100 m = 29,800 m in 92 seconds so its speed was approx. 323.9 m/s.

We require 331m/s + 0.6m/s/C * T = 323.9 m/s

T = - 11.8 deg. C

If (2), the sound travelled 2 x 150 x 100 m = 30,000 m in 92 seconds so its speed was approx. 326.1 m/s.

We require 331m/s + 0.6m/s/C * T = 326.1 m/s

T = - 8.2 deg. C

This seems very cold. You may wish to check my working. I am sure my basic idea is correct though.

Explanation: