A grasshopper leaps into the air at a 62° angle above the horizontal, and follows a parabolic arc in free fall after it leaves the ground. Mark all of the following that are true at the top of that parabolic arc? a. The grasshopper is in equilibrium at the top of the arc.
b. The grasshopper's total velocity vector is zero.
c. The grasshopper's acceleration vector is zero.
d. None of the above.

d. None of the above.

Explanation:

In a parabolic motion, you have that in the complete trajectory the component velocity is constant and the vertical component changes in time. Then, the total velocity vector is not zero.

In the complete trajectory the gravitational acceleration is always present. Then, the grasshopper's acceleration vector is not zero.

At the top of the arc the grasshopper is not at equilibrium because the gravitational force is constantly acting on the grasshopper.

Then, the correct answer is:

d. None of the above.