Practice Thermal Equilibrium in Physics

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

Thermal equilibrium is the state in which objects in thermal contact have reached the same temperature, so there is no net transfer of thermal energy between them.

When two objects stop getting warmer or cooler because they have matched temperatures, they are in thermal equilibrium.

Showing a random 20 of 50 problems.

Example 1

hard

1

kg of ice at

0^\circ

C is added to

2

kg of water at

80^\circ

C. Assume the ice melts completely. (

L_f = 334000

J/kg,

c_w = 4200

J/kg·

^\circ

C.) Find the equilibrium temperature.

Example 2

challenge

An insulated tank holds

5

kg of water at

60^\circ

C. Hot water at

80^\circ

C is added until the tank temperature is

70^\circ

C. Find the mass of hot water added.

Example 3

easy

Two objects are in thermal contact. Thermal equilibrium is reached when what is true of their temperatures?

Example 4

challenge

0.1

kg of steam at

100^\circ

C is bubbled through

1

kg of water at

20^\circ

C until all the steam condenses and equilibrium is reached. (

L_v = 2.26\times 10^6

c_w = 4200

.) Find the final temperature.

Example 5

hard

0.5

kg of steam at

100^\circ

C is condensed into

2

kg of water at

20^\circ

C. (

L_v = 2.26\times 10^6

J/kg,

c_w = 4200

J/kg·

^\circ

C.) Find the equilibrium temperature.

Example 6

medium

1

kg of water at

20^\circ

C is in a

0.3

kg aluminium pan (

c = 900

) at

20^\circ

C. A burner adds

20000

J. Find the final temperature.

Example 7

easy

Object A is at

50^\circ\text{C}

, object B at

30^\circ\text{C}

. Which way does heat flow when they touch?

Example 8

easy

200

g of water at

80^\circ

C is poured into

200

g of water at

20^\circ

C. Find the equilibrium temperature.

Example 9

medium

0.3 \text{ kg}

aluminium spoon (

c=900

) at

20^\circ\text{C}

is placed in

0.5 \text{ kg}

of soup (

c=4000

) at

80^\circ\text{C}

. Find the equilibrium temperature.

Example 10

hard

0.2

kg block of aluminium (

c = 900

) at

T

is placed in

0.6

kg water at

25^\circ

C (

c = 4200

). Equilibrium is

30^\circ

C. Find

T

Example 11

medium

Equal masses of two liquids (

c_A = 2000

c_B = 4000

) at

80^\circ

C and

20^\circ

C respectively are mixed. Find the equilibrium temperature.

Example 12

easy

1

kg of water at

40^\circ

C is mixed with

3

kg of water at

0^\circ

C. Find the equilibrium temperature.

Example 13

hard

0.4

kg of ice at

-10^\circ

C is added to

1

kg of water at

40^\circ

C. (

c_{\text{ice}} = 2100

L_f = 334000

c_w = 4200

.) Find the equilibrium temperature.

Example 14

medium

Why does a large lake change temperature more slowly than a small puddle under the same sunlight?

Example 15

medium

A large lake at

15^\circ

C and a teaspoon of water at

15^\circ

C are in thermal equilibrium. Which has more internal (thermal) energy?

Example 16

medium

0.5

kg block at

80^\circ

C is placed in

0.5

kg water (

c = 4200

) at

20^\circ

C and they settle at

25^\circ

C. Find the block's specific heat.

Example 17

medium

2 \text{ kg}

of water at

80^\circ\text{C}

mixes with

3 \text{ kg}

30^\circ\text{C}

. Find the equilibrium temperature.

Example 18

hard

Equal masses of two metals X (

c_X = 600

) at

100^\circ

C and Y (

c_Y = 200

) at

20^\circ

C are placed in contact (no other losses). Find the equilibrium temperature.

Example 19

easy

Three objects, each in thermal equilibrium with a fourth, are mixed together. Their temperatures are _____.

Example 20

medium

Heat flows between two objects until equilibrium. Object A loses

800

J. Object B's temperature rises by

4^\circ

C with

c = 1000

J/kg·

^\circ

C. Find object B's mass.

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Related Concepts

Heat Transfer Temperature Specific Heat Capacity