Vo = 20m/s[50o]
Xo = 20*cos50 = 12.9 m/s
Yo = 20*sin50 = 15.3 m/s.
V = Vo + g*Tr = 0 @ max Ht.
Tr = -Yo/g = -15.3/-9.8 = 1.56 s. = Rise
time.
h = Yo*Tr + 0.5g*Tr^2
h max = 15.3*1.56 - 4.9*1.56^2=11.9 m.
h = 0.5g*t^2 = 11.9-3.04 = 8.90 m.
4.9t^2 = 8.90
t^2 = 1.82
Tf = 1.35 s. = Fall time.
a. Dx = Xo*(Tr+Tf) = 12.9 * (1.56+1.35) = 37.5 m.
D = 37.5-36 = 1.5 m to spare
b. Falling.
a place kicker must kick a football from a
Lint 36 meters from the goal. As a result of the kick, the ball must clear the crossbar, which is 3.04 meters high. When kicked, the ball leaves the ground with a speed of 20 meters per second at an angle of 50 degrees to the horizontal.
By how much does the ball clear or fall short of clearing the crossbar?
Does the ball approach the crossbar while still rising or falling?
1 answer