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Projectile Motion Question

  • Thread starter jumbogala
  • Start date
  • #1
423
2

Homework Statement



An insect is resting above the water level on a leaf, a horizontal 0.600 m away from a fish. The fish shoots water into the air above the surface of the water at a 60 degree angle, with an initial velocity of 3.01 m/s.

Assume the fish shoots the water into the air at water level, and that the water hits the insect.

At what height is the leaf above water level?

Homework Equations


v = vi + at
v= d/t
x = vi(t) + 0.5a(t^2)

The Attempt at a Solution


First I tried to find out how much time it would take the water to travel in the horizontal direction.

Initial velocity in horizontal direction: cos60*3.01= 1.505 m/s
With zero acceleration, the time it would take to travel 0.600 m would be:
t=0.600/1.505=0.398 s

Then, I tried to figure out where the water would be at 0.398 seconds vertically.
Its initial velocity is sin60*3.01 = 2.60 m/s
2.60(0.398)+(0.5)(-9.81)(0.398^2)= 0.259 m

I must be doing something wrong because the program says I have the wrong answer. I have no idea where the problem is, though... any ideas?
 

Answers and Replies

  • #2
Hootenanny
Staff Emeritus
Science Advisor
Gold Member
9,622
6
You have rounded at the intermediate steps, which has induced errors in your final answer. Try to use the exact values of the intermediate steps by either storing them in your calculator, or writing down the full calculator display.
 
  • #3
423
2
Thanks, I think that solves the problem.
 

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