If the length of an activity is greater than 150 seconds, the energy system is predominately used.

If the lenght of an activity is greater than 150 seconds, the AEROBIC GLYCOLYSIS energy system is predominantly used.
There are two way by which energy is produced in the body through glycolysis, aerobically and anaerobically. The aerobical method is the normal route of energy production, but the muscles in addition to been able to produce energy aerobically, can also produce energy anaerobically, that is, in the absence of oxygen. This form of energy is usually produced in the muscles when energy are needed for a job of very short duration. When the duration of the job is more than 150 seconds, aerobic glycolysis of energy production will be used.

The particles of the gas inside the ball heats up, bouncing off each other and spreading farther apart.hope my answer has you : )

D. the index of refraction of the second medium is lower.