NEED HELP Which BEST explains why it is important to warm up before strenuous exercise?
A.
It is very hard on the joints when exercise begins without warm up.
B.
It strains the muscles if blood and oxygen levels are not already activated.
C.
Warm-ups limit the oxygen supply, prepping the body for the rush during exercise.
D.
An exercise session should not include more than 30 minutes of aerobic activity.

An air bubble of volume 20 cm³ is at the bottom of a lake 40 m deep, where the temperature is 4.0°c. the bubble rises to the surface, which is at a temperature of 20°c.take the temperature of the bubble’s air to be the same as that of the surrounding water. just as the bubble reaches the surface, what is its volume?

Alinearly polarized electromagnetic wave has an average intensity of 196 w/m^2. this wave is directed towards two ideal polarizers (in real polarizers, transmission is also effected by reflection and absorption). polarizer a is oriented with its transmission axis at an angle of θ_1=20.8∘ with the incident electric field. polarizer b has its axis at an angle of θ_2=63.0∘ with the incident electric field. what is the average intensity of the wave after it passes through polarizer a? what is the average intensity of the wave after it passes through polarizer b? suppose that the two polarizers a and b are interchanged. what would the average intensity be after passing through both polarizers?

What energy transformations occur each time the skateboarder rolls up the ramp?