No, flexeril is a muscle relaxant. The drug name is cyclobenzaprine. Ibuprofen is a non-steroidal anti-inflammatory pain medicine. You can safely take a pain reliever and a muscle relaxant together. They work together to help reduce your discomfort.
This force exerted by air molecules or what is called as Atmospheric pressure is measured by barometer. At sea level the amount of pressure exerted by the atmosphere is about 14.7 pounds/square inch. This means at sea level an object experiences 14.7 pounds of pressure pushing against every square inch of object. When heat energy is added to molecules, they begin to move rapidly. This causes the molecules to exert increased pressure as they bump into the objects around them.
The units of psig (pounds per square inch, gage) remind us that we are talking about this *difference* in pressure. The absolute air pressure at sea level is about 14.7 psi. Suppose the air pressure in your car tire is 30 psig. Then the absolute pressure inside is 30+14.7 = 44.7 psi.