4 Hz is the difference between 510 and the unknown.
<span>Therefore the unknown is either 514 or 506. </span>
<span>If 505 and 506 were struck together, the diff would be 1 Hz </span>
<span>If 505 and 514 were struck toghether, the diff would be 9 Hz which would be difficult to count accurately, </span>
<span>Therefore the unknown is 514</span>
From the freezing temperature up to about 4°C (39°F) the water CONTRACTS. That is, it becomes MORE dense. I think I read that water is the ONLY known substance whose solid phase floats in its liquid phase. That's why the cubes float in your soda and bergs float in the ocean. And if weren't so, then life on Earth would not be possible ! Oceans and lakes would freeze from the bottom up, ONE TIME, and then never thaw again.
The answer is (B. The study of Matter and Energy) but technically you could consider physics all of these as engineering is based on physics and that would be the study of inventions, chemistry and biology were both discovered because of physics, and physics invokes more math than any other subject as it applies math to the entire Universe.
