Question

Falling objects drop with an average acceleration of -9.8 m/s2. If an object falls from rest from a tall building, how long will it take before it reaches a speed of -49 m/s?

Answer 1

It will take t = 5 [s]

Step-by-step explanation:

To solve this problem we must use the following equation of kinematics, it is important to make it clear that when the object is dropped, its initial velocity is zero.

Let's take all the signs of the equation as positive, since the object falls in the direction of motion.

`v_(f) =v_(o) +(g*t)`

where:

Vf = final velocity = 49 [m/s]

Vo = initial velocity = 0

g = gravity acceleration = 9.81 [m/s²]

t = time [s]

49 = 0 + 9.81*t

t = 49/9.81

t = 5 [s]