The British thermal unit (BTU or Btu) is a traditional unit of work equal to about 1055 joules. It is the amount of work needed to raise the temperature of one pound of water by one degree Fahrenheit (Physical analogue: one four-inch wooden kitchen match consumed completely generates approximately 1 BTU). BTU is the amount of heat required to raise the temperature of 1 avoirdupois pound of liquid water by 1 degree Fahrenheit at a constant pressure of one atmosphere. calorie, several definitions of the BTU exist, because the temperature response of water to heat energy is non-linear.
When an object free falls, it does not encounter a significant force of air resistance. Always Some Air Resistance. However, a falling object is going to run into some degree of air resistance. Air resistance is the outcome of collisions between the objectâs leading surface and air molecules. How much air resistance the object encounters depends on the speed the object is traveling and the cross sectional area of the object. When the object is falling faster, this increases air resistance.
The amount of air resistance an object experiences depends on its speed, its cross-sectional area, its shape and the density of the air. Air densities vary with altitude, temperature and humidity. Nonetheless, 1.29 kg/m3 is a very reasonable value. The shape of an object affects the drag coefficient (Cd).