If the kicker gives the ball the same initial speed and angle but the ball is ki
ID: 1395708 • Letter: I
Question
If the kicker gives the ball the same initial speed and angle but the ball is kicked from a point 22 m from the goalpost, what is the height of the ball above the crossbar as it crosses over the goalpost? Figure 1 Express your answer in meters to two significant figures. 20.0 m/s - 4.8 30.0 Submit My Answers Give Up The ball will have sufficie nt height to clear the goalpost at two different values of x. However, only the height at r = d describes the ball on its way back down. Incorrect Iry Again, 4 attempts remainingExplanation / Answer
from equation:, Sx = ux*t + ( 1/2) *ax*t2
22 = u*cos30 * t + 0 ( u= initial velocity = 20m/s)
t = 22 / 20*cos 30
t ( time) = 1.27 sec
Sy = uy*t + ( 1/2) * ay* t2
h = u*sin 30* t - ( 1/2) * 9.8 * ( 1.27)2 ( a = -g)
h = 4.79 m
this is the vertical distance travelled by ball.
the height of ball above the cross bar can be calculated as:
= vertical distance of ball - height of crossbar
= 4.79 - height of crossbar
put the value of height of cross bar ( which is not given in the Q ) to get the result.
b) Vy ( final vertical velocity of ball) = ?
Vy = uy + ay t
= u*sin30 - g*t
= 20*sin30 - 9.8 * 1.27
= - 2.446 m/s