Projectile motion of a cannon ball

  • Thread starter Ry122
  • Start date
  • #1
565
2
a ball is fired from a cannon at an angle of 40 degrees to the horizontal and it travels 300m before hitting the side of a cliff which is 10 meters higher than the cannons position.
Determine the initial velocity.

The ball has a negative velocity when it hits the cliff.

My attempt:
Where v = the balls initial velocity
y component of velocity = -9.81t + Vsin40

integrate this and get

y position = .5*-9.8t^2 + vsin40t

x component of velocity = vcos40

integrate this and get

x position = vcos40t


Using the expression for x velocity, solve for t at 300m in the x direction and get the expression
t=300/vcos40

Sub this into the expression for the y position above and solve for v.


I'm unsure if this is the correct way to go about doing this. The velocity I ended up with is 42.7124ms^-1 which seems a bit slow for the distance it covers.
 

Answers and Replies

  • #2
25
0
Your method is correct.
I check your answer, but I got the initial speed is 48.8 m/s.
 

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