Originally Posted by

**henryNZ** Here is the question,

Two bungy jump operators are conducting an experiment to estimate the length of the latex rubber required, when full extended, for a safe vertical jump off the bridge,

OP1 drops a boulder from the bridge, uses a stopwatch to time how long it takes before he **sees** the splash in the river below. This takes 4.2 seconds.

OP2 does the same, uses a stopwatch but he times how long it takes before he __hears__ the splash. This takes 4.5 seconds.

The relationship between the distance the boulder has fallen and the time take is d=4.9t^2. The speed of sound in air is 344m/s.

Their final estimate of the safe distance is the mean of their estimates, less a 5m saftey margin.

Can anyone help me with this please, apparently it is a quadratic that is solved by completing the square.