A football player kicked a ball with an initial velocity of 20 m/s at an angle from the ground.
1. What is the velocity at its peak of flight of the football?
2. What is the horizontal velocity of the football one second after it is being kicked?
3. What is the vertical acceleration of the football one second after it reached its peak?
4. What will happen to the vertical velocity of the football as it falls to the ground?
5. What will happen to the horizontal velocity of the football as it falls to the ground?
Answers & Comments
Answer:
A football is kicked at an angle of 37 degrees with a velocity of 20 m/s.
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You didn't spec the Earth's gravitational acceleration.
I'll use 10 m/sec/sec
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Calculate:
a.) Maximum height
Vertical component Vv = 20*sin(37) =~ 12.036 m/sec
Flight time = 12.036*2/10 = 2.407 seconds
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h(t) = -5t^2 + 12.036t
Max is the vertex @ t = -b/2a = 12.036/10 = 1.2036 seconds
h(1.2036) = 7.243 meters Max height
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b.) The time of travel before the ball hits the ground
2.407 seconds
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c.) The range
Horizontal component = 20*cos(37) =~ 15.973 m/sec
range = 15.973*2.407 = 38.45 meters
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d.) The velocity vector at the maximum height
= Horizontal component at angle zero (no vertical speed)
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e.) The acceleration vector at the maximum height
= -5 m/sec/sec at all times