Exam 13: First Law of Thermodynamics

A 6.5-g iron meteor hits Earth at a speed of 295 m/s.If its kinetic energy is entirely converted to the thermal energy of the meteor,by how much will its temperature rise? The specific heat of iron is 113 cal/kg ∙ C°,and 1 cal = 4.186 J.

An ideal gas undergoes the process a→b→c→a shown in the pV diagram.The thermal energy transferred to the gas through heating gas in process a→b is 546 J,while in process $b \rightarrow c$ the gas loses 62.0 J of thermal energy through heating.In process a→b there is - $310 \mathrm {~J}$ of work performed on the gas,while in process c→a 223 J of work is done on the gas.How much heat is gained by the gas in process c→a?

A substance has a melting point of 20°C and a heat of fusion of 3.4 × $10^4$ J/kg.The boiling point is $150 ^ { \circ } \mathrm { C }$ and the heat of vaporization is $6.8 \times 10^4 \mathrm {~J} / \mathrm { kg }$ at a pressure of one atmosphere.The specific heats for the solid,liquid,and gaseous phases are 600 J/kg ∙ K (solid),1000 J/kg ∙ K (liquid),and 400 J/kg ∙ K (gaseous).How much thermal energy is required to raise the temperature of $1.90 \mathrm {~kg}$ this substance from $- 4 ^ { \circ } \mathrm { C }$ to $106 ^ { \circ } \mathrm { C }$ at a pressure of one atmosphere?

A 0.600-kg piece of metal X is heated to 100°C and placed in an aluminum can of mass 0.200-kg which contains 0.500 kg of water initially at 17.3°C.The final equilibrium temperature of the mixture is 20.2°C,what is the specific heat of metal X? The specific heats of water and aluminum are 4186 J/kg ∙ K (water)and 910 J/kg ∙ K (aluminum).

A person is walking outdoors on a cold day when the temperature is -20°C.He is breathing at the rate of 16 breaths per minute,and each time he breathes in he inhales 0.0050 m³ of air.At what rate does he lose thermal energy by breathing if the air in his lungs is heated to body temperature (37°C)before it is exhaled? The specific heat of air is 1020 J/kg ∙ K and the density of air is 1.29 kg/m³.

A 200-L electric water heater uses 2.0 kW.Assuming no thermal energy loss,how many hours would it take to change the temperature of water in this tank from 23°C to 75°C? The specific heat of water is 4186 J/kg ∙ K and its density is 1000 kg/m³.

Object 1 has three times the specific heat capacity and four times the mass of Object 2.The same amount of energy is transferred to each object though the process of heating.If the temperature of Object 1 changes by an amount ΔT,the change in temperature of Object 2 will be

Which one of the following quantities is the smallest unit of thermal energy?

A glass beaker of unknown mass contains $74.0 \mathrm { ml }$ of water.The system absorbs $2000.0 \mathrm { cal }$ of thermal energy and the temperature rises $20.0 ^ { \circ } \mathrm { C }$ as a result.What is the mass of the beaker? The specific heat of glass is 0.18 cal/g ∙ °C,and that of water is 1.0 cal/g ∙ C°.

Two processes are shown on the pV diagram in the figure.One of them is an adiabat and the other one is an isotherm.Which process is the isotherm?

The melting point of aluminum is 660°C,its latent heat of fusion is 4.00 × 10⁵ J/kg,and its specific heat is 900J/kg ∙ K.How much thermal energy must be added to 500 g of aluminum originally at 27°C to completely melt it?

A 600-g piece of iron at 100°C is dropped into a calorimeter of negligible specific heat containing 100 g of ice at 0°C and 120 g of water,also at 0°C.What is the final temperature of the system? The specific heat of iron is 448 J/kg ∙ K,the latent heat of fusion of water is 33.5 × 10⁴ J/kg,and the specific heat of water is 4186 J/kg ∙ K.

A metal has a latent heat of fusion of 2.32 × 10⁴ J/kg,a specific heat of 128 J/kg ∙ K,and a melting point of 228°C.A 30-g pellet of this metal at 16°C hits a solid wall and comes to a complete stop.What would the speed of the pellet have to be in order for it to melt completely when it hits the wall,assuming that all of its kinetic energy is transformed into thermal energy within the pellet?

A gas is taken through the cycle shown in the pV diagram in the figure.During one cycle,how much work is done by the gas?

A substance has a melting point of 20°C and a heat of fusion of $3.6 \times 10^4 \mathrm {~J} / \mathrm { kg }$ The boiling point is $150 ^ { \circ } \mathrm { C }$ and the heat of vaporization is $7.2 \times 10^4 \mathrm {~J} / \mathrm { kg }$ at a pressure of one atmosphere.The specific heats for the solid,liquid,and gaseous phases are 600 J/kg ∙ K (solid),1000 J/kg ∙ K (liquid),and 400 J/kg ∙ K (gaseous).How much thermal energy is emitted by $2.80 \mathrm {~kg}$ of this substance when it is cooled from 170°C to 86°C at a pressure of one atmosphere?

A 360-g metal container,insulated on the outside,holds 180.0 g of water in thermal equilibrium at 22.0°C.A 24.0-g ice cube,at the melting point,is dropped into the water,and when thermal equilibrium is reached the temperature is 15.0°C.Assume there is no thermal energy exchange with the surroundings.For water,the specific heat is 4190 J/kg ∙ K and the heat of fusion is 3.34 × 10⁵ J/kg.What is the specific heat of the metal of the container?

If you add 700 kJ of thermal energy to 700 g of water originally at 70.0°C,how much water is left in the container? The latent heat of vaporization of water is 22.6 × $10 ^ { 5 }$ J/kg,and its specific heat capacity is 4186 J/kg ∙ K.

A beaker of negligible heat capacity contains 456 g of ice at -25.0°C.A lab technician begins to supply thermal energy through the process of heating to the container at the rate of 1000 J/min.How long after starting will the ice begin to melt,assuming all of the ice has the same temperature? The specific heat of ice is 2090 J/kg ∙ K and the latent heat of fusion of water is 33.5 × 10⁴ J/kg.

A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper,with the aluminum and the copper in thermal contact.The specific heat capacity of aluminum is more than double that of copper.Which object will have the greater magnitude gain or loss of internal energy during the time the system takes to reach thermal equilibrium?

When 50 g of a certain material at 100°C is mixed with 100 g of water at 0°C,the final temperature is 40°C.What is the specific heat of the material? The specific heat of water is 1.00 kcal/kg ∙ C°.