Projectile motion in serious need of help

  • Thread starter DJ-Smiles
  • Start date
  • #1
47
0
I need loads of help, i have a physics test on friday and have been studying vigorously; i havent been lazy and have been working fopr 8 weeks, i tried to do this question and i have no clue HELP ME PLEASE!!!

Homework Statement



A place-kicker must kick a football from a point
36.0 m (about 40 yards) from the goal, and half the crowd
hopes the ball will clear the crossbar, which is 3.05 m high.
When kicked, the ball leaves the ground with a speed of
20.0 m/s at an angle of 53.0° to the horizontal. (a) By how
much does the ball clear or fall short of clearing the crossbar?
(b) Does the ball approach the crossbar while still rising
or while falling?

The Attempt at a Solution


Ok so i found the velocity of the x component using simple trig but then im in trouble with the next step. i have absolutely no clue at all i tried to find the time it takes to cover the x displacemetn at the x velocity then used that time to find the overall displacement.
 

Answers and Replies

  • #2
49
2
Solve the y displacement instead using the time you got. The time you got is the time at which the ball is at x = 36.0 m, so the next step would be to calculate the height of the ball at that time. Then compare that height to the height of the crossbar and answer question a.
 
  • #3
47
0
thank you sooo much You honestly dont know how much that means i was stressing out big time because the test is thursday and im fixing up my weaker points...

I did what you said and the answer is correct

Once again thanks so much
 

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