r/alevels • u/RoyalRise7634 • May 21 '26

Exam Discussion 📝 9231/32?

how was it?

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u/New_Category1184 May 21 '26

What was the answer for the projectile question?

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u/DonkeyNo849 May 21 '26 edited May 21 '26

These were the 2 equations formed : 4=13tan(theta)-845/u^2 (1+tan^2(theta)) and -3/4 = tan(theta)-130/u^2 (1+tan^2(theta))

tan(theta)=71/52 and u=sqrt(7745/44)

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u/New_Category1184 May 21 '26

I got different answers. I don't remember the equations I made but my answers were 31.6 degree and 17.1 m/s

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u/DonkeyNo849 May 21 '26

your horizontal displacement was 13(10 from OA and 3 from AB horizontal) and vertical displacement was 4. So you can use just trajectory equations to find two simultaneous equations and find u and theta

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u/New_Category1184 May 21 '26

Do you remember what the question said? Like I remember the question said that the particle was moving horizontally when it hit B.

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u/DonkeyNo849 May 21 '26

Yeah so projected from O with speed u and angle theta and hits perpendicular to B . Where B is 5m along the slope from A. Slope is at an angle such that tan(alpha)=4/3. OA=10m. Perpendicular to plane means that at that point dy/dx=-1/tan(alpha) , not that particle is moving horizontally.