Syllabus Edition

First teaching 2014

Last exams 2024

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Thermal Concepts (DP IB Physics: SL)

Exam Questions

3 hours44 questions
1
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1 mark

In the table below, which row shows the correct conversion between the Kelvin and Celsius temperature scales?

  Kelvin temperature / K Celsius temperature / °C
A. 0 –270
B. -273 0
C. 150 -123
D. 210 -163

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    2
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    1 mark

    Thermal energy is transferred from a solid. Three properties of the solid are 

    1. Specific heat capacity
    2. Mass
    3. Area

    Which of the above properties determine the decrease in temperature of the solid?

    • II only

    • I and III only

    • I and II only

    • I only

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    3
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    What are the units of the ratio fraction numerator s p e c i f i c space l a t e n t space h e a t space o f space f u s i o n space o f space i r o n over denominator s p e c i f i c space h e a t space c a p a c i t y space o f space i r o n end fraction?

    • J K

    • No units

    • K–1

    • K

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    4
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    1 mark

    The strength of intermolecular forces varies between in the different states of matter.

    What is the order from highest to lowest strength of intermolecular forces?

    • solid > liquid > gas

    • solid > gas > liquid

    • liquid > gas > solid

    • gas > liquid > solid

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    5
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    1 mark

    Molecules fuse from water vapour to form water. The vapour and the water have the same temperature.

    What is the change of the average potential energy and the change of the average random kinetic energy of these molecules when they move from the vapour to the water?

      Average potential energy Average random kinetic energy
    A. decreases decreases
    B. no change decreases
    C. decreases no change
    D. no change  no change

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      6
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      1 mark

      Which of the following correctly identifies the properties of the molecules of a substance that determine the substance’s internal energy?

      • The total gravitational potential energy and random electrostatic potential energy

      • The total potential energy and random kinetic energy

      • The random kinetic energy

      • The total potential energy

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      7
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      1 mark

      The specific latent heat of vaporisation is the energy required to change the phase of

      • one kilogram of a liquid to gas.

      • a solid at constant temperature.

      • one kilogram of a gas to liquid at constant temperature.

      • a gas at constant temperature.

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      8
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      1 mark

      A sample of solid aluminium is heated beyond its melting point. The graph shows the variation of temperature with time.

      3-1-q8-sl-easy-mcq-phy

      During which stage(s) is the aluminium melting?

      • Q only

      •  P, Q and R

      • P only

      • P and R only

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      9
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      1 mark

      What is the correct comparison of the specific latent heat of fusion Lf to the specific latent heat of vaporisation Lfor any substance?

      • L= Lv

      • Lf Lv

      • Lf Lv

      • Depends on the substance.

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      10
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      1 mark

      Which of the following is numerically equal to the specific heat capacity of a substance?

      • The thermal energy required to increase the temperature of unit mass of the substance by 1 °C

      • The thermal energy required to increase the temperature of the substance by 1 °C

      • The sum of the random kinetic and potential energy of all the molecules in the substance

      • The thermal energy required to evaporate the substance

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      1
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      1 mark

      Liquid iron solidifies without a change in temperature.

      Which of the following is correct for the molecules in the solid phase compared with molecules in the liquid phase?

       

      Potential energy

      Kinetic energy

      A.

      same

      same

      B.

      same

      less

      C.

      less

      less

      D.

      less

      same

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        2
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        1 mark

        A liquid is initially at its boiling point. Energy is continuously supplied to the liquid at a uniform rate until it has completely evaporated.

        Which graph shows how the temperature of the liquid, T, varies with the energy, Q, supplied to the liquid?

        q13_thermal-concepts_ib-sl-physics-mcq

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          3
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          In a refrigerator, 2 kg of water cools from 30 °C to 0 °C and then freezes to form ice also at 0 °C. The whole process takes 4000 seconds.

          The specific heat capacity of water is 4200 J kg−1 K−1.

          The specific latent heat of fusion of ice is 3.4 × 105 J kg−1.

          What is the power required by the refrigerator during this process?

          • 233 W

          • 240 W

          • 932 W

          • 260 W

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          4
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          1 mark

          A 2 kW kettle supplies energy to a water of mass 1 kg. The initial temperature of the water is 20 °C. The specific heat capacity of water can be taken to be 4000 J kg–1 K–1.

          How long does it take for the water to start boiling?

          • 80 s

          • 120 s

          • 160 s

          • 210 s

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          5
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          1 mark

          A substance loses energy at a constant rate. The graph shows how the temperature, T, of the substance varies with time, t, as the state of the substance changes from liquid to solid. 

          q16_thermal-concepts_ib-sl-physics-mcq

          What can be deduced about this substance from the graph shown?

          • The specific latent heat of fusion of the substance is greater than its specific latent heat of vaporization

          • The specific heat capacity of the liquid is lower than the specific heat capacity of the solid

          • The specific latent heat of fusion of the substance is less than its specific latent heat of vaporization

          • The specific heat capacity of the liquid is greater than the specific heat capacity of the solid

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          6
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          1 mark

          Aluminium melts at 660 °C. A mass m of solid aluminium is initially at a temperature of 645 °C. The aluminium is heated and melts into liquid aluminium and continues to be heated up to a final temperature of 720 °C.

          • Specific latent heat of fusion of aluminium = Lf
          • Specific heat capacity of solid aluminium = cS
          • Specific heat capacity of liquid aluminium = cL

          Which expression gives the energy needed for this change to occur?

          • m(15cS + Lf + 60cL)

          • m(cS + 15Lf + 75cL)

          • m(15cS + 60Lf + cL)

          • m(15cS + Lf + 75cL)

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          7
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          1 mark

          The graph shows how the temperature T of a liquid varies with energy Q supplied to the liquid at a constant rate P.

          The gradient of the graph is z and the liquid has a specific heat capacity, c.

          q18_thermal-concepts_ib-sl-physics-mcq

          What is the mass of the liquid?

          • z c

          • fraction numerator 1 over denominator z c end fraction

          • p over c

          • z over c

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          8
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          1 mark

          A sealed cylinder contains water at 10 °C and ice at 0 °C. The system has been thermally isolated from the surroundings. The ice and the water reach thermal equilibrium.

          What happens to the total internal energy of the system in order for equilibrium to be reached?

          • It reduces

          • It increases

          • It increases until the ice has melted and then remains constant

          • It remains constant

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          9
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          1 mark

          A flask contains a mass m of a fluid. When 2000 J of heat is provided the temperature of the water and the flask increases by 10 K.

          The mass of the fluid is doubled, and the experiment is repeated. This time 4500 J is required to increase the temperature by 10 K.

          The specific heat capacity of the fluid is 5000 J kg–1 K–1.

          What is the value of m

          • 5 g

          • 25 g

          • 40 g

          • 50 g

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          1
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          1 mark

          1 kg of water at 20 °C cools to 0 °C and then freezes to form ice, also at 0 °C.

          What is the energy released during this process?

          You may use the following values:

          • Specific heat capacity of water = 4000 J kg–1 K–1
          • Specific latent heat of fusion of ice = 3.4 × 105 J kg–1
          • 1.1 × 105 J

          • 3.0 × 105

          • 4.2 × 105

          • 5.0 × 105

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          2
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          1 mark

          Heat energy is supplied at a constant rate to a solid material with a specific heat capacity of 1.92 × 103 J kg−1 K−1.

          question-7

          What is the specific latent heat of fusion of the substance?

          • 2.6 × 105 J kg−1

          • 9.6 × 104 J kg−1

          • 4.48 × 104 J kg−1

          • 1.92 × 103 J kg−1

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          3
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          1 mark

          The temperature of 500 g of water decreases by Δ°C when placed in a fridge for 10 minutes. This container of water is then removed and a second container of mass 250 g and temperature 25 °C is placed in the same fridge for 20 minutes. 

          Assume that the containers holding the water are identical and do not emit or absorb energy. The specific heat capacity of water is 4200 J kg−1 K−1.

          What is the final temperature of the second container of water after 20 minutes?

          • 25 space minus space 4 increment T space

          • 25 space minus space 3 increment T space

          • 25 space plus space 4 increment T space

          • 4 increment T space

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          4
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          1 mark

          An engine goes through 6000 cycles every minute. To maintain a constant working temperature, 152 J of energy must be removed by a coolant during each complete cycle of the engine. The temperature of the coolant rises by 20 °C as it passes through the engine. 

          The specific heat capacity of the coolant is 3.8 × 10J kg−1 K−1 and the density is       1000 kg m−3.

          What is the volume of the coolant that flows through the engine in one second?

          • 3 × 10−5 m3

          • 1 third cross times 10 to the power of negative 8 end exponent m3

          • 12 × 10−3 m3

          • 2 × 10−4 m3

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          5
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          1 mark

          A glass beaker of water contains an immersion heater completely submerged by the water and is placed on the right-hand side of a two-pan balance. The heater boils the water at    100 °C and is connected to a kWh meter. When the water starts to boil standard masses are added to the left-hand side of the balance so it is in equilibrium with the water. At this moment the reading on the meter is 11.3 kWh. 

          A 400 g mass is then added to the left-hand side of the balance, causing it to tilt. As the water boils off the right pan rises until it is once again in equilibrium. When this happens the new reading on the meter is 11.5 kWh.

          question-13

          What is the specific latent heat of vapourisation of the steam if the heater is 50% efficient?

          • 3.6 × 105 J kg−1

          • 1800 J kg−1

          • 9 × 105 J kg−1

          • 250 J kg−1

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          6
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          1 mark

          A spring in a ball point pen has a mass of 0.10 g and a specific heat capacity of             400 J kg−1 K−1 and a spring constant k = 200 N m−1. To open or close the nib of the pen the spring is compressed by 8 mm. Upon release 5% of the elastic potential energy stored is converted into heat energy in the spring.

          How many times must the spring be compressed and released to cause the temperature of the pen to increase by 2 °C?

          Assume that no heat is lost from the pen. 

          • 250

          • 80 000

          • 250 000

          • 100

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          7
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          1 mark

          An ice cube of mass mi and temperature −Ti is dropped into a glass of water of mass mw and temperature Tw. The specific heat capacity of ice is ci and the specific latent heat of fusion of ice is Li. The specific heat capacity of water is cw.

          What is the final temperature of the water?

          • fraction numerator m subscript w c subscript w T subscript w plus space m subscript i left parenthesis c subscript i T subscript i plus L subscript i right parenthesis over denominator m subscript w c subscript w minus space m subscript i c subscript i end fraction

          • fraction numerator m subscript w c subscript w T subscript w minus m subscript i left parenthesis c subscript i T subscript i plus L subscript i right parenthesis over denominator m subscript w c subscript w plus m subscript i c subscript w end fraction

          • fraction numerator m subscript w c subscript w T subscript w minus space m subscript i L subscript i over denominator m subscript w c subscript w plus m subscript i c subscript i end fraction

          • fraction numerator m subscript w c subscript w T subscript w minus m subscript i left parenthesis c subscript i T subscript i plus L subscript i right parenthesis over denominator m subscript i c subscript i end fraction

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          8
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          1 mark

          A sample of a solid is heated with a heater of constant power.

          3-1-sl-mcq-hard-q8-phy

          What is the power of the heater?

          • fraction numerator 9 m c over denominator 30 end fraction W

          • fraction numerator 7 m c over denominator 150 end fractionW

          • fraction numerator 2 m c over denominator 5 end fraction W

          • fraction numerator 7 m c over denominator 30 end fraction W

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          9
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          1 mark

          Two bodies of equal mass A and B are brought into thermal contact. Object A has a temperature of  0 °C and object B has a temperature of 100 °C. Object A has a specific heat capacity greater than object B. No other exchanges of heat take place.

          Which statement is correct?

          • 0 < < 50 °C

          • = 50 °C

          • = 75°C

          • 50 °C < < 100 °C

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          10
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          1 mark

          Energy is provided to a solid at its melting rate of joules per second. The rate at which the mass is melting away is α kg per second. 

          What is the specific latent heat of fusion of the solid?

          • alpha over P

          • αP

          • fraction numerator 1 over denominator alpha P end fraction

          • P over alpha

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