'a', 'b', and 'c' are all reasonable statements.
Answer:
4
Explanation:
The weight of the rock is W = mg = (80 kg) (10 m/s²) = 800 N.
The mechanical advantage is therefore 800 N / 200 N = 4.
She can put chalk in vinegar as the vinegar will disintegrate the chalk chemically demonstrating chemical changes. But for physical changes she can break the chalk into small pieces by smashing it with something or her hand.
The word to fill in the blank is "equal". Because the time taken to rotate (spin on its axis) is equal to the time of revolution (going around the earth), this means that both have the same rate of angular rotation. So for every bit that the moon goes around its orbit around earth, the moon itself rotates accordingly to present the exact same side to earth.
