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# Projectile problem watch

1. A projectile is launched at speed U at an angle theta. Calculate x(t) and y(t).

So far I've written out:

For the horizontal:
S = x
U = Ucos(theta)
V = Ucos(theta)
A = 0
T = ?

Vertical (at top point):
S = y
U = Usin(theta)
V = 0
A = -9.81
T = ?

I think I need to use s = ut +0.5at^2
However I seem to do it I get loads of unknowns.

I got: x= (dx/dt)cos(theta)t +0.5(d^2x/dt^2)t^2 but I don't know what theta is?
2. (Original post by Lunu)
...
What exactly does the question say? I'm not entirely sure what you are aiming to find, I'm assuming its an algebraic expression, as you have no values to calculate with.
3. (Original post by Phichi)
What exactly does the question say? I'm not entirely sure what you are aiming to find, I'm assuming its an algebraic expression, as you have no values to calculate with.
It wants me to find x and y in terms of t so yeah an algebraic expression I think. It's for a differential equations module.
4. (Original post by Lunu)
It wants me to find x and y in terms of t so yeah an algebraic expression I think. It's for a differential equations module.
You have:

and

I'm confused exactly what they are asking for. You have just from knowledge the x and y displacement in terms of t.
5. (Original post by Phichi)
You have:

and

I'm confused exactly what they are asking for. You have just from knowledge the x and y displacement in terms of t.
A projectile is launched at a speed U at an angle θ to the horizontal from (x, y) = (0, 0).Thereafter the projectile moves so that x¨ = 0, y¨ = −g, where g is the acceleration due togravity (9.81 ms−2 on the surface of the Earth). Calculate x(t), y(t) and y as a function ofx.

That is the complete question

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