Question

Suppose for the previous problem you choose your coordinate system so that the opposite direction is positive. a. What is the brick's velocity after $4.0 {s} ?$ b. How far does the brick fall during this time?

Answer 1

The brick's velocity after 4.0 seconds is -39.2 m/s. The brick falls a distance of 78.4 m during this time.

Step-by-step explanation:

In the previous problem, we have a brick that falls under the influence of gravity. In this case, the coordinate system is chosen so that the opposite direction is positive. We can determine the brick's velocity after 4.0 seconds by using the equation:

v = u + at

where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time. Since the only force acting on the brick is gravity (which causes it to accelerate), we can use the equation:

a = -g

where g is the acceleration due to gravity. Plugging in the values, we get:

v = u + at

v = 0 + (-9.8 m/s^2) imes 4.0 s

v = -39.2 m/s

Therefore, the brick's velocity after 4.0 seconds is -39.2 m/s.

To determine how far the brick falls during this time, we can use the equation:

s = ut + (1/2)at^2

where s is the distance, u is the initial velocity, a is the acceleration, and t is the time. Plugging in the values, we get:

s = 0 imes 4.0 + (1/2)(-9.8 m/s^2)(4.0 s)^2

s = -78.4 m

Therefore, the brick falls a distance of 78.4 m during this time.