Which type of energies make up the mechanical energy of a roller coaster moving along a track?

Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?

Only 3% of the water on earth is usable by humans. even though that 3% is through the water cycle, we still need to be careful not to waste water.

Use henry's law and the solubilities given below to calculate the total volume of nitrogen and oxygen gas that should bubble out of 1.7 l of water upon warming from 25 ˚c to 50 ˚c. assume that the water is initially saturated with nitrogen and oxygen gas at 25 ˚c and a total pressure of 1.0 atm. assume that the gas bubbles out at a temperature of 50 ˚c. the solubility of oxygen gas at 50 ˚c is 27.8 mg/l at an oxygen pressure of 1.00 atm. the solubility of nitrogen gas at 50 ˚c is 14.6 mg/l at a nitrogen pressure of 1.00 atm. assume that the air above the water contains an oxygen partial pressure of 0.21 atm and a nitrogen partial pressure of 0.78 atm.