Question

NEED ANSWER ASAP PLEASE!!!!!!!
#23-24 deal with objects that fall from rest due to gravity. Vi=0 and A=9.8 m/s/s

23. A piece of pipe drops off of a building and has been falling for 7 seconds. What is its final velocity (in m/s)?

24. If a ball falls from rest from the top of a tall building and reaches a velocity of 49 m/s, how long will it take (in s) before the ball reaches the ground?

Answer 1

In both questions, the objects are falling from rest so their final velocities after time $t$ will be given by

$v_f=v_i+at=at$

where $a$ is the acceleration due to gravity given. Note that I take the downward direction to be positive.

23.

$v_f=\left(9.8\,\dfrac{\mathrm m}{\mathrm s^2}\right)(7\,\mathrm s)\implies v_f=68.6\,\dfrac{\mathrm m}{\mathrm s}$

24.

$49\,\dfrac{\mathrm m}{\mathrm s}=\left(9.8\,\dfrac{\mathrm m}{\mathrm s^2}\right)t\implies t=5.0\,\mathrm s$