A ball is dropped from the roof of a building. How fast is it moving after 4.5 seconds? (Absolute value)

V = Vo + gt = 0 + 9.8*4.5 = 44.1 m/s.

To find the speed of the ball after 4.5 seconds, we need to know the acceleration due to gravity. On Earth, the acceleration due to gravity is roughly 9.8 meters per second squared (m/s^2). Assuming no air resistance, we can use this value to find the final speed of the ball.

To calculate the speed, we can use the equation:

v = u + at

Where:
v = final velocity
u = initial velocity (in this case, the ball is initially at rest, so u = 0)
a = acceleration due to gravity (taking the negative sign as the ball is moving downwards)
t = time

Plugging in the known values, we have:

v = 0 + (-9.8 m/s^2) * 4.5 s

Using this equation, we can find the final velocity of the ball after 4.5 seconds.