Question

4. One kicks a football upward. On the way up, it passes the roof of a building at height $h$ in time $t$ after the kick. What is the total time the football is in the air, from when it was kicked to when it lands back on the ground? (1) $\frac{2h}{gt} + t$ (2) $\frac{2h}{gt} - t$ (3) $\frac{h}{gt} + t$ (4) $\frac{h}{gt} - t$ (5) $\frac{h}{gt} + 2t$ Make y-axis go up and y=0 at the ground level. 1D motion with constant acceleration: $y_f = y_i + v_it + \frac{1}{2}at^2$ In this problem: At the time the ball passes the roof: $h = 0 + v_it - \frac{1}{2}gt^2$ At the time when the ball lands back on ground: $0 = 0 + v_iT - \frac{1}{2}gT^2$ Two equations, two unknowns ($v_i$ and $T$): one can solve for both.

          4. One kicks a football upward. On the way up, it passes the roof of a building at height $h$ in time $t$ after the kick. What is the total time the football is in the air, from when it was kicked to when it lands back on the ground?
(1) $\frac{2h}{gt} + t$
(2) $\frac{2h}{gt} - t$
(3) $\frac{h}{gt} + t$
(4) $\frac{h}{gt} - t$
(5) $\frac{h}{gt} + 2t$
Make y-axis go up and y=0 at the ground level.
1D motion with constant acceleration:
$y_f = y_i + v_it + \frac{1}{2}at^2$
In this problem:
At the time the ball passes the roof:
$h = 0 + v_it - \frac{1}{2}gt^2$
At the time when the ball lands back on ground:
$0 = 0 + v_iT - \frac{1}{2}gT^2$
Two equations, two unknowns ($v_i$ and $T$): one can solve for both.

4. One kicks a football upward. On the way up, it passes the roof of a building at height h in time t after the kick. What is the total time the football is in the air, from when it was kicked to when it lands back on the ground?
(1) (2h)/(gt) + t
(2) (2h)/(gt) - t
(3) (h)/(gt) + t
(4) (h)/(gt) - t
(5) (h)/(gt) + 2t
Make y-axis go up and y=0 at the ground level.
1D motion with constant acceleration:
yf = yi + vit + (1)/(2)at^2
In this problem:
At the time the ball passes the roof:
h = 0 + vit - (1)/(2)gt^2
At the time when the ball lands back on ground:
0 = 0 + viT - (1)/(2)gT^2
Two equations, two unknowns (vi and T): one can solve for both.

Added by Loretta C.

University Physics with Modern Physics

Hugh D. Young 14th Edition

Thanks for your feedback!

One kicks a football upward. On the way up, it passes the roof of a building at height h in time t after the kick. What is the total time the football is in the air, from when it was kicked to when it lands back on the ground? 2h (1) + t It 2h (2) gt h. 3 h h (5) + 2t gt 4 26 Make y-axis go up and y=0 at the ground level 1D motion with constant acceleration: Yf = Yi + vit + at In this problem: h = 0 + vt - 0.5gt^2 At the time the ball passes the roof: At the time when the ball lands back on the ground Two equations, two unknowns (v and t): one can solve for both.