How much does the kinetic energy change is the speed of an object is tripled and its mass is cut in half

Let's take the initial mass of the object = m
velocity = v
initial KE = 1/2 mv² = 0.5mv²

Now the velocity is trippled
V = 3v
mass is cut in half
M = 0.5m
final KE = 1/2 MV² = 1/2 x (0.5m) x (3v)² =9/4 mv² = 2.25 mv²

Change in KE = 2.25mv² - 0.5mv² = 1.75mv²
% change = (Change in KE/initial KE) x 100
                 = (1.25mv²/0.5mv²) x 100
                 = (1.25/0.5) x 100
                 =250%

Change in kinetic energy is 250%

Hope it helps!

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.