physics help please? MicroJoules?

[princess]

A large glider of 287.4 grams colliding with a small stationary glider of 134.8 grams. After the collsion, the two gliders are stuck together, moving at a common speed of 0.134 m/s. The velocity of the stuck-together gliders after the collision is measured with a photogate that records the time, during which a small flag mounted on top of the gliders blocks the light beam of the photo gate while the gliders move through the gate.

You have estimated that the 5.6 cm width of the flag has a 1 mm error. You neglect the error of the time measurement, and estimate that the error of the mass measurements are 1 gm each? Can you neglect the contribution of the mass measurements in your estimate of the error of the final kinetic energy? If so, indicate your answer (below) with a negative sign; otherwise leave the sign positive.

What is the absolute error of the total kinetic energy? Express your amswer in microJoules.