1. (Units) a unit of heat in the fps system equal to the quantity of heat required to raise the temperature of 1 pound of water by 1Â°F. 1 British thermal unit is equivalent to 1055.06 joules or 251.997 calories.
Quick Answer. A major factor that usually causes tire noise is the air chamber inside the tire. The large void that is filled with air acts as a giant resonance chamber. Thus, the tires are something like donut-shaped drums that generate a low-frequency hum when tires are rolling.
Whistling Noise. Hi. yesterday my car started making an unsual whistling noise. when i accelerate it starts off failry quiet however as the revs build up, the sound gets louder and higher pitched. It also sounds like air is leaking out of somewhere but we cant decide where from.