Aiden takes 0.10 s to throw a baseball, which leaves his hand with a velocity of 40 m/s. the ball's acceleration is

Acceleration (A) = V(final)-V(initial)/TThe unit for acceleration is metres/second squared (m/s^2).

You're already given Velocity (V) = 40 m/s in the question, so just plug in the values.

A= 40/0.10
A= 400 m/s^2. 

Julia would be observing a. static electricity was caused by her sweater rubbing against her shirt and transferring electrons. she didn't touch anything metal, so that would cancel out b.she most likely didn't rub her sweater against her hair either, so that cancels out c.she also didn't scoot across the carpet while trying to take her sweater off, that cancels out d.so that leaves a.a. is correct.