# How do you determine the height for Part B of this question?

##### 1 Answer

#### Explanation:

Let height of the building be

After the wrench is dropped from the roof top, the kinematic equation is given by

where

Let us find out the distance dropped when workman standing at the eighth floor observes the wrench. (for simplicity eyes of worker assumed at the floor level)

Since the floors above the first are of height

Hence number of floors above the eighth floor

Total number of floors of the building

We need to remember that the workman standing on the eighth floor has only seven floors below him.

Height of the building

(First floor is of

From (1) velocity

Kinetic energy of wrench when it hits the ground

(All its potential energy while at the roof gets converted into its kinetic energy as it hits the ground.

It can also be calculated using the expression