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# Again another stupid projectile watch

1. 18) A particle is projected from a point with position vector (3i+3j)m relative to a fixed origin O where i and j are unit vectors in the horizontal and upward vertical directions respectively. Two seconds later the particles passes through the point with position vector (13i+8j)m. Find its initial velocity vector.
2. (Original post by Deep456)
18) A particle is projected from a point with position vector (3i+3j)m relative to a fixed origin O where i and j are unit vectors in the horizontal and upward vertical directions respectively. Two seconds later the particles passes through the point with position vector (13i+8j)m. Find its initial velocity vector.
Vertically:
s=5
a=-9.8
t=2
u=?

Horizontally:
s=10
a=0
t=2
u=?

Use an equation to work out the initial speed horizontally and the initial speed vertically.
3. (Original post by starofale)
Vertically:
s=5
a=-9.8
t=2
u=?

Horizontally:
s=10
a=0
t=2
u=?

Use an equation to work out the initial speed horizontally and the initial speed vertically.
s=ut+1/2at^2

Resolving vertically:
5=2u-19.6
24.6=2u
12.3=u

Resolving horizontalyl:
10=2u
u=5
4. (Original post by Deep456)
s=ut+1/2at^2

Resolving vertically:
5=2u-19.6
24.6=2u
12.3=u

Resolving horizontalyl:
10=2u
u=5
Yes, so its velocity vector would be 5i + 12.3j

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