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# M2 help!! watch

1. Could someone help me with part c of this question I don’t even know where to start

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2. (Original post by Mf1999)
Could someone help me with part c of this question I don’t even know where to start
First of all.. how did you manage to capture such a blurry image in 2018?
Not sure if u have learned about the dot product of vectors, but that is one way to find the velocity perpendicular to the initial velocity. Here are the steps:
1. Split the initial velocity into horizontal and vertical components. (Let's call them Ux & Uy)
2. The velocity at Q will be Vx & Vy, after using dot product on the 2 vectors, for both of them to be perpendicular, Ux * Vx + Uy * Vy =0
3. Solve the equation in 2. and get the displacement from the velocity (Vy & Vx).
3. original velocity = ai + bj

perpendicular velocity = bi - aj

acceleration = 0i - 9.8j

bi - aj = ai + bj + (0i - 9.8j)t

====> b - a = 0

a = 7
b = 7c

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i am actually getting a value for c

c = 1

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