Physics question

[ramminghard]

A kicker running at 7.5 m/s kicks the football straight out in front of him so that it travels with an initial velocity of 20 m/s at an angle of 50degrees above the horizontal. If the kicker continues to run at 7.5 m/s in the origonal direction, how far will he from the ball when it lands?

[infamous]

he will be sitting in the stands drinking a beer. :thumbsup:

holy shit i can't even remember any of the math shit that i took in school....

[Marsh]

i dont remember the formula's exactly but you need to break the footballs speed into components ( the Vy and Vx) with simple geometry, and at the top of the parabola of the football(all trajectories travel in parabolic motion) Vy will be zero so then you can figure out time/distance/height? something like that(god i wish i rememberd the formulas) so using that you can find the time when the ball will land/distance it travels/ or when height will return back to zero. Then you can figure out the distance the runner travelled easily, and you should be able to derive the distance that both of them are apart

I know this probably doesn't seem to helpful( i dont even know what the hell im tlaking about) but i'll try to find formulas from my old worksheets and post something better when i get a chance

Hope that helped though ramminghard

[rc2002]

59.02m

[rc2002]

Vertical velocity of ball after kicked = 20*sin(50) = 15.32m/s. Gravity is acting on this velocity so vertical velocity - (acceleration due to gravity * time) = 0. Time to top = 5.51. Time to top and then to bottom again = 5.51 * 2 = 11.02.

Horizontal velocity of ball = 20*cos(50) = 12.86m/s.

Horizontal velocity * time = distance ball travels = 141.67m.

The runner runs at 7.5m/s for 22.05s. Distance runner travels = 82.65m.

Difference = 59.02m.

[ramminghard]

Originally posted by richardchan2002
Vertical velocity of ball after kicked = 20*sin(50) = 15.32m/s. Gravity is acting on this velocity so vertical velocity - (acceleration due to gravity * time) = 0. Time to top = 5.51. Time to top and then to bottom again = 5.51 * 2 = 11.02.

Horizontal velocity of ball = 20*cos(50) = 12.86m/s.

Horizontal velocity * time = distance ball travels = 141.67m.

The runner runs at 7.5m/s for 22.05s. Distance runner travels = 82.65m.

Difference = 59.02m.

Thanks a lot for the help!:thumbsup:

[Marsh]

No thanks to me?
DIE:guns: :rofl: :rofl:

[ramminghard]

Originally posted by Marsh
No thanks to me?
DIE:guns: :rofl: :rofl:

Thanks!!!;)

[Marsh]

hahaha your welcome!