Finding max height and acceleration vector for projectile

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Vibhor
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Homework Statement



Text problem: a projectile thrown at 60 degrees with 20 m/s, H at highest point; particle P moves along same trajectory with increasing speed, P at H has v = 20 m/s, acceleration 50 m/s^2; find acceleration vector at H (g = 10). Answer given: (30i - 40j) m/s^2.


Homework Equations





The Attempt at a Solution



Maximum height attained by first projectile H = u2sin2θ/2g = 15m

If acceleration vector is assumed a = axi+ayj , then at H √(ax2+ay2) = 50 .

Now I need to use the given conditions to come up with another equation . Not sure how to proceed .

Please help me with the problem .
 
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  • Typed physics problem: a projectile thrown at 60 degrees to the horizontal with speed 20 m/s, H the highest point; particle P at H has v = 20 m/s and acceleration 50 m/s^2; find acceleration vector a at H (g = 10). Answer shown: (30i - 40j) m/s^2.
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Last edited:
Figure out the centripetal acceleration at that point. Hint: Use the fact that the first projectile is at its apex at the point H.
 
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Hi Doc

Your suggestion has worked nicely .Thanks a lot :smile:.

I was just wondering what do we infer from the third line in the problem " such that the speed is increasing continuously ". We didn't make any use of it .

Your thoughts ?
 
Vibhor said:
I was just wondering what do we infer from the third line in the problem " such that the speed is increasing continuously ". We didn't make any use of it .
You make use of that fact in determining the direction of the horizontal acceleration component. It tells you that ax is positive.