Question

Points: 4 14) A ball is thrown horizontally with an initial velocity of 20.0 m/s from the edge of a building of a certain height. The ball lands at a horizontal distance of 80.0 m from the base of the building. (2 points) a) What is the height of the building? Write yor answer here with units b) What is the speed of the ball when it hits the ground? Write yor answer here with units _(2 points) Show work for full credit

Answer 1

distance travelled in x direction

Sr urt + at 2

ат = 0

= 20 20t +-oxt 2

t = 4sec

distance in y direction

$s_y=u_yt+\frac{1}{2}a_yt^2$

$u_y=0$

$a_y=g$

$s_y=h$

$h=0 \times 4+\frac{1}{2}g \times {4}^2$

(b) velocity when hit the ground

in x direction

ат = 0

in y direction

$v_y= 0+10\times 4= 40$

$v=\sqrt{v_x^2+v_y^2}$

$v=\sqrt{{20}^2+{40}^2}$

$v=20\sqrt{5}m/sec$