Question

A brick is dropped (zero initial speed) from the roof of a building. The brick strikes the ground in 1.90 s. You may ignore air resistance, so the brick is in free fall. How tall, in meters, is the building? What is the magnitude of the brick's velocity just before it reaches the ground?

Answer 1

The height of the building can be calculated using the time of free fall and the equation of motion for objects with constant acceleration due to gravity. The magnitude of the brick's velocity just before impact is also determined through the kinematic equation for constant acceleration.

Step-by-step explanation:

To solve for the height of the building from which the brick was dropped, we can use the equation of motion s = ut + (1/2)at². Since the brick is dropped with zero initial speed (u = 0) and it is in free fall, the only acceleration is due to gravity (a = g = 9.8 m/s²). So the height of the building (s) can be calculated using the time (t = 1.90 s) it takes for the brick to reach the ground.

Therefore, the height of the building is calculated as follows:
s = 0 m/s × 1.90 s + (1/2) × 9.8 m/s² × (1.90 s)²

The magnitude of the brick's velocity just before it reaches the ground (v) can be calculated using the equation v = u + at.

So the velocity just before impact is: v = 0 m/s + 9.8 m/s² × 1.90 s