Physics Help Forum Magnitude of Initial velocity of Spacecraft

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

 Feb 7th 2013, 06:05 PM #1 Junior Member   Join Date: Jan 2013 Posts: 4 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)
 Feb 7th 2013, 07:21 PM #2 Member   Join Date: Jan 2013 Posts: 42 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.
 Feb 7th 2013, 08:00 PM #3 Junior Member   Join Date: Jan 2013 Posts: 4 I got 1.14 and 1.20, but it say neither are correct
 Feb 8th 2013, 05:10 AM #4 Physics Team     Join Date: Jun 2010 Location: Morristown, NJ USA Posts: 2,347 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).
 Jul 1st 2013, 12:30 AM #5 Junior Member   Join Date: Jul 2013 Posts: 1 I will try this method, thanks for shairng. __________________ pagerank checker | primarkonlineshopping.net