For each of the following, decide which forms of energy are present: a leaf falls from a tree; a candle burns; a rubber band is wrapped around a newspaper.
A roller coaster car with a mass of 500 kg is at the top of a hill that is 30 m high. Without friction, what would its kinetic energy be as it reached the bottom of the hill?
How does heat differ from thermal energy?
2007-05-21 09:38:25 · 5 answers · asked by maosportz 2 in Science & Mathematics ➔ Physics
The air gets heated (the tyres get heated because of friction with the road and that heat is transmitted to the air inside the tube). And with increasing temperature, the air pressure inside gets higher.
Kinetic energy (potential energy is getting transformed when it starts falling), Heat energy (candle burning is a chemical reaction), potential energy (rubber is stretched elastically)
The kinetic energy will be 1/2 mv^2 = mgh where m is the mass, g the acceleration due to gravity and h the height. In this case, we can assume g = 10 m/sec^2 to keep the maths simple. So we have 500 X 10 X 30 = 150000 Joules
How does heat differ from thermal energy?
Heat is thermal energy but sentient heat or temperature is a measure of the temperature gradient, just as water at a higher level flows to a lower level, heat flows from a higher temperature to a lower temperature. The thermal energy or heat capacity of a body is given by mass X specific heat X temperature (above absolute zero).
At absolute zero, all thermal motion stops and the heat energy of a body is zero. Though approached closely, absolute zero has not been attained.
2007-05-21 09:50:17 · answer #1 · answered by Swamy 7 · 0⤊ 0⤋
The pressure in the tyre is directly proportional to the temperature of the air. Put simply, if the temperature increases (which will happen during an hours drive) then the pressure will also increase. Note that to calculate values the temperature must be in kelvin (0 kelvin = 273 degrees celsius). You would then use P1/T1 = P2/T2.
2007-05-21 09:55:35 · answer #2 · answered by Sec 4 · 0⤊ 0⤋
tire has friction with road surface
friction causes heat
heat expands air in a enclosed area so pressure goes up
2007-05-21 09:45:05 · answer #3 · answered by Jo Blo 6 · 0⤊ 0⤋
falling leaf is kinetic energy...stretched rubber-band is potential energy
2007-05-21 09:47:19 · answer #4 · answered by johnfarruca 2 · 0⤊ 0⤋
the heat that builds in the tire pressure
2007-05-21 09:42:22 · answer #5 · answered by babytat44 1 · 0⤊ 0⤋