What do we have in common with the animals that we hunt

An object weigh 40n in air ,weigh 20n when submerged in water,and 30n when submerged in a liquid of unknown liquid density.what is the density of unknown of liquid?

Explain the difference in reactivity of the elements based on their electron configurations.

No matter what energy transformation we discuss, we know that no energy transfer is 100% efficient. you are about to enter a bicycle rave. you have trained extensively and eaten well to maximize your energy input throughout the bicycle race. you know that some of your kinetic energy will become wasted energy in the form of heat. what is the source of the heat energy and how can you minimize it to maximize the efficiency of your performance in the race? a) you are the source of the heat energy. you can minimize the heat energy but selecting the appropriate clothes to wear. b) air resistance is the source of he heat energy. you can minimize the air resistance by your position while riding the bicycle. c) friction is the source of the heat energy. you can minimize the friction by lubricating all appropriate parts and keeping the tires well inflated. d) kinetic energy is the source of the heat energy. you can reduce the production of heat energy but minimizing the energy you expend to race on the bicycle.