A soccer player kicks the ball toward a goal that is 28.0 m in front of him. The ball leaves his foot at a speed of 19.5 m/s and an angle of 30.6° above the ground. Find the speed of the ball when the goalie catches it in front of the net. (Note: The answer is not 19.5 m/s.)

So i assume you find the horizontal component of Vi and solve for t which i got 1.6682. Then substitute 1.6682 for t while solving final velocity of vertical component. Use pythogereom thereom and get the final velocity. I got an answer of 15 m/s but the computer says is wrong. Please help it would mean alot!

1 answer

u = horizontal component = 19.5 cos 30.6
= 16.8 m/s the whole time

so time in air = 28/16.8 = 1.67 seconds

What is vertical component?
Vi = 19.5 sin 30.6 = 9.93 m/s
but
v = Vi - g t
v = 9.93 - 9.81(1.67)
v = -6.46 m/s headed down

total speed = sqrt (16.8^2+6.46^2)
= 18 m/s