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Old Feb 7th 2013, 06:05 PM   #1
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Post Magnitude of Initial velocity of Spacecraft

On a spacecraft two engines fire for a time of 572 s. One gives the craft an acceleration in the x direction of ax = 5.15 m/s2, while the other produces an acceleration in the y direction of ay = 7.41 m/s2. At the end of the firing period, the craft has velocity components of vx = 3782 m/s and vy = 4842 m/s. Calculate the magnitude of the initial velocity.

Attempt
add the square root of 3782 and the square root of 4842
take the square root of the sum 131.082
=11.42 m/s(incorrect)
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Old Feb 7th 2013, 07:21 PM   #2
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Wouldn't you just use these equations:

vy=voy+a*t

vx=vox+a*t
?

Last edited by toranc3; Feb 7th 2013 at 07:30 PM.
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Old Feb 7th 2013, 08:00 PM   #3
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I got 1.14 and 1.20, but it say neither are correct
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Old Feb 8th 2013, 05:10 AM   #4
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Use the method toranc3 suggested, to find the x and y components of the initial velocity, v0x and v0y. The magnitude of the initial velociy is then sqrt(v0x^2+v0y^2).
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Old Jul 1st 2013, 12:30 AM   #5
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I will try this method, thanks for shairng.
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