Answer and Explanation:
a. An oxygen-filled balloon is not able to float in the air, because the oxygen inside the balloon is of the same density, that is, the same "weight" as the oxygen outside the balloon and present in the atmosphere. The balloon can only float if the gas inside it is less dense than atmospheric oxygen. Helium gas is less dense than atmospheric gas, so if a balloon is filled with helium gas, that balloon will be able to float because of the difference in density.
b. The ship is able to float in the water because its steel construction is hollow and full of air. This makes the average density of this ship less than the density of water, which makes the ship lighter than water and for this reason, this ship is able to float. In addition, the ship is partially immersed, allowing the weight of the ship on the water to counteract the buoyant force that the water promotes on the ship. Weight and buoyant are two opposing forces that keep the ship afloat.
Answer: Exercise Physiology
Explanation:
Answer:
The equatiom of kinetic energy is 1/2×m×v² where m represents mass and v is velocity :

The unit for kinetic energy is measured in Joules (J).
Complete Question
The complete question is shown on the first uploaded image
Answer:
the value of 
Explanation:
From the question we are told that
The equation is (x + y = 40)
The first value of x is 
The second equation is (0.75x + 1.5y = 40)
So substituting 

=> 
Now substituting y and
into second equation

=> 
So 
The answer to number 1 is D and the answer for the second one is 2
^-^