Applying+Math

The air in a living room has a mas of 72kg and a specific heat of 1,010J/(kg°C). What is the change in thermal energy of the air when it warms form 20°C to 25°C?

Q = m x (Tf-Ti) x °C Q = (72kg)(25°C — 20°C)(1,010kg x °C) Q = 363,600J

Calculate the change in thermal energy of the water in a pond with a mass of 1,000 kg and a specific heat of 4,184 J/(kg °C) if the water cools by 1 °C.

Q=m(Tf - Ti)C Q=1,000 kg x- 1°C x 4,184 J/kg°C=(cools) Q= -4,184,000J

Calculate the specific heat of a metal if 0.5 kg of the metal absorb 9,000 J of heat as it warms by 10°C.

9,000 J = (0.5 kg)(10°C)(C) = 9,000(0.5)(10°C) =1,900 J(kg°C)

Calculate change in thermal energy: You push down in the handle of a bicycle pump with a force of 20N. The handle moves 0.3 m, and the pump does not absorb or release any heat. What is the change in thermal energy of the bicycle pump?

Q=m(Tf-Ti)C Q=20N (0.3) Q=6J

Calculate Work The thermal energy release when a gallon of gasoline is burned in a car's engine is 140 million J. If the engine is 25% efficient, how much work does it do when one gallon of gasoline is burned?140,000,000J is released when a gallon of gas is burned. The engine is 25% efficient.

140,000,000J 25% efficient 140,000,000x.25= 35.000.000J