Exam 13: First Law of Thermodynamics

The figure shows a pV diagram of a gas for a complete cycle.During part bc of the cycle,1190 J of thermal energy through the process of heating flows into a system,and at the same time the system expands against a constant external pressure of $7.00 \times 10^4 \mathrm {~Pa}$ as its volume increases from $0.0200 \mathrm {~m} ^ { 3 }$ to $0.0800 \mathrm {~m} ^ { 3 }$ Calculate the change in internal (thermal)energy of the system during part bc of the cycle.If the change is nonzero,be sure to indicate whether the change is positive or negative.

The gas in a perfectly insulated but there is work done on the flexible container at a rate of - $13 \mathrm {~W} .$ At what rate is the internal (thermal)energy of the gas changing?

A lab assistant pours 330 g of water at 45°C into an 855-g aluminum container that is at an initial temperature of 10°C.The specific heat of aluminum is $900 \mathrm {~J} / \mathrm { kg } \cdot \mathrm { K } ,$ and that of water is 4186 J/kg ∙ K.What is the final temperature of the system,assuming no thermal energy is exchanged with the surroundings?

A gas expands from an initial volume of 0.040 m³ to a final volume of 0.085 m³ while its pressure increases linearly with the volume (so that the process follows a straight-line path in a pV diagram)from 110 kPa to 225 kPa.How much work is done on the gas during this expansion?

The process shown on the TV graph in the figure is an

An athlete doing push-ups performs 650 kJ of work and loses 425 kJ of thermal energy through heating.What is the change in the internal (thermal)energy of the athlete?

The figure shows a pV diagram for an ideal gas that is carried around a cyclic process.How much work is done on the gas in one cycle if p₀ = $4.00 \mathrm {~atm}$ and $\mathrm { V } _ { 0 } = 3.00$ L? (1.00 atm = 101 kPa)

During an isothermal process,5.0 J of thermal energy via the process of heating is removed from an ideal gas.What is the work done on the gas in the process?

A person tries to heat up her bath water by adding 5.0 L of water at 80°C to 60 L of water at 30°C.What is the final temperature of the bath water?

How much energy must be added to a 8.0-kg block of ice at -8°C to change it to water at $14 ^ { \circ } \mathrm { C } \text { ? }$ The specific heat of ice is 2050 J/kg ∙ C°,the specific heat of water is 4186 J/kg ∙ C°,the latent heat of fusion of ice is 334,000 J/kg,and 1 cal = 4.186 J.

The melting point of aluminum is 660°C,its latent heat of fusion is 4.00 × 10⁵ J/kg,and its specific heat is 900 J/kg ∙ K.If 300 kJ of thermal energy are added to 442 g of aluminum at 100°C,what is the final state of the system? That is,how much is liquid,how much is solid,and what is its temperature?

The work done on an ideal gas system in an isothermal process is -400 J.What is the change in internal (thermal)energy of the gas?

A .20-kg ice cube at 0.0°C has sufficient thermal energy added to it through the process of heating to cause total melting,and the resulting water is heated to $70.0 ^ { \circ } \mathrm { C }$ How much energy is added? For water L_F = 334,000 J/kg,L_V = 2.256 × 10⁶ J/kg,the c = 4.186 x 10³ J/kg ∙ C.

The process in which thermal energy flows by the mass movement of molecules from one place to another is known as

A solid concrete wall has dimensions 4.0 m × 2.4 m and is 30 cm thick.The thermal conductivity of the concrete is 1.3 W/m ∙ K,and it separates a basement from the ground outside.The inner surface of the wall is at 18°C,and the outside surface is at 6°C.How much thermal energy flows through the wall every hour?

During an isothermal process,5.0 J of thermal energy via the process of heating is removed from an ideal gas.What is the change in internal (thermal)energy of the gas?

A runner generates 1260 W of thermal energy.If this energy has to be removed only by evaporation,how much water does this runner lose in 15 minutes of running? The latent heat of vaporization of water is 22.6 × 10⁵ J/kg.

In an isochoric process,the internal (thermal)energy of a gas decreases by 50 J.How much work is done on the gas during this process?

A person consumes a snack containing 14 food calories (14 kcal).What is the power this food produces if it is to be "burned off" due to exercise in 6 hours? (1 cal = 4.186 J)

An external heat source supplies thermal energy through heating to a system at a rate of 187 W as the environment does work on the system at a rate of -131 W.At what rate is the internal (thermal)energy of the system changing?