science education teaching

Estimating the Distance to Lightening Yr 9 Light Estimating the Distance to Lightening There is a simple rule to calculate the distance lightening is from us, just because sound and light travel at different speeds! For every ____ seconds that we measure between when we see the lightening to when we hear the thunder the lightening is another 1km away. Some facts; Thunder is generated when lightening occurs Thunder travels at the speed of sound (in air) Lightening travels at the speed of light (in air) There are 1000 m in every 1 km Time Taken = Distance Travelled / Speed If the lightening/thunder is 10 km away. Calculate how long it takes the sound and light to reach us in seconds, round to the nearest second. Sound: Light: Is the time taken by the sound much longer than the time taken by the light? Can we ignore the time taken by the light (is it negligible)? First Rule: If we count ____ seconds between when we see the lightening to when we hear the thunder, we will know that the lightening was 10km away. R Laugesen 16/07/2008 Estimating the Distance to Lightening Yr 9 Light That’s a good rule, but what if we measure more or less time between our lightening and our thunder? We need a more general rule. Calculate how long the sound from the thunder takes to reach us if the lightening is only 1 km away? How many seconds is this, If we round the answer to 0 decimal places? Now go back to the box at the start and enter the number of seconds you calculated. Extra optional exceptionally tough section: How far does the thunder travel in 1 second? How long does it take the thunder to travel 1 m? R Laugesen 16/07/2008