Question

A stone is dropped from a bridge and hits the water in 4.0 s. How high is the bridge?

Answer 1

Answer:

first, u find the change in speed, which is acceleration due to free fall times the time taken

so change in speed=10m/s^2 * 4.0s = 40m/s (assuming acceleration due to free fall is 10m/s^2 and ignoring air resistance)

now, u find the average speed, which is (40m/s+0m/s)/2=20m/s

[(initial speed +final speed)/2 is the average speed]

distance (or height) = average speed times time= 20m/s * 4.0s = 80m

so that s the height og the bridge