Question

a bridge is 38 feet above a river. how many seconds does it take a rock dropped from the bridge to pass by a tree limb that is 10 feet above the water?

Answer 1

Answer:it will take 1.32 seconds

Step-by-step explanation:

The height of the bridge above the river is 38 feet

The height of the tree limb above the river is 10 feet

Disaster from the bridge to the tree limb = 38 - 10 = 28feet. The rock will travel 28feet before it passes the tree limb. To determine the time, we will apply Newton's equation of motion.

h = ut + 1/2 ×gt^2

where

h = height of the rock

t = time taken for the rock to fall

u = initial velocity of the rock.

g = acceleration of the object and it is also acceleration due to gravity.

From the information given,

h = 28 feet

g = 32.2ft/s^2

u = 0(velocity of the rock starts from 0 and increases as it keeps falling)

28 = 0×t + 1/2 × 32.2 × t^2

28×2 = 32.2 × t^2

t^2 = 56/32/2 = 1.74

t = √1.74 = 1.32 seconds