Question

A construction worker drops a brick off a high scaffold. If the brick lands 5.0 s later, how fast was the brick travelling the instant before hitting the ground?

Answer 1

The brick was traveling at 49 m/s the instant before hitting the ground.

Step-by-step explanation:

When an object is dropped from rest in a free-falling motion, it falls with a constant acceleration called the acceleration of gravity, which value is
`g = 9.8 m/s^2`.

The final velocity of a free-falling object after a time t is given by:

`vf=g.t`

The distance traveled by a dropped object is:

`\displaystyle y=(gt^2)/(2)`

The brick takes 5 seconds to land from the high scaffold. The speed at which it lands is:

`vf=9.8\cdot 5`

vf=49 m/s

The brick was traveling at 49 m/s the instant before hitting the ground.