Spacecraft Acceleration Question

[Lokhtar]

Homework Statement

On a spacecraft , two engines are turned on for 684s at a moment when the velocity of the craft has x and y components of Vox=4370 m/s and Voy = 6280 m/s. When the engines are firing, the craft undergoes a displacement that has components of x= 4.11x10^6m and y = 6.07x10^6m. Find the x and y components of the craft's acceleration.

Homework Equations

D = Vo*t + 1/2 at^2

The Attempt at a Solution

For X:
4.11*10^6m = 4370m(684s) + 1/2 a(684s)^2 = 4.79m/s^2

For Y:
6.07*10^6m = 6280m(684s) + 1/2 a(684s)^2 = 7.56m/s^2

The answers given are 17.6m/s^2 and 25.9m/s^2, but I am not sure why. I'd appreciate any help.

 

[Redbelly98]

For X:
4.11*10^6m = 4370m(684s) + 1/2 a(684s)^2 = 4.79m/s^2

What is this "= 4.79m/s^2" all about? You're saying that

4.11*10^6m = 4.79m/s^2

which is false. The units don't even match.

Just solve the equation for "a". (And forget the 4.79m/s^2 part).

p.s. you probably know this, but the 4370m should have different units.