Question

You drop a stone down off a bridge. You are able to count to 4.0 seconds when it finally hits the water. How high is the bridge?​

Answer 1

The height of the bridge above the water is 78.4 meters.

Step-by-step explanation:

To find the height of the bridge, we can use the equation for freefall motion. The distance fallen by an object in freefall is given by the equation d = 1/2gt^2, where d is the distance fallen, g is the acceleration due to gravity, and t is the time. In this case, the time is 4.0 seconds and the distance fallen is the height of the bridge. Rearranging the equation to solve for height, we have h = 1/2gt^2. Plugging in the values of g = 9.8 m/s^2 and t = 4.0 seconds, we can calculate the height of the bridge to be:

h = 1/2 * 9.8 m/s^2 * (4.0 s)^2 = 78.4 meters

Answer 2

The height of the bridge is 78.4 m.

Step-by-step explanation:

Given;

time of the stone motion off the bridge, t = 4.0 s

acceleration due to gravity, g = 9.8 m/s²

The height of the bridge is given by;

h = ut + ¹/₂gt²

where;

u is the initial velocity of the stone, u = 0

h = ¹/₂gt²

h = ¹/₂(9.8)(4)²

h = 78.4 m

Therefore, the height of the bridge is 78.4 m.