Physics 11th Chap 8 : Topic 6 - Maryam Publications

Physics Chapter 8 : Topic 6

Work Done by a Gas

1 / 40

The work done when a gas expands at constant pressure is given by:

A) $\mathbf{W =}$ $\frac{\mathbf{\mathrm{\Delta}V}}{\mathbf{p}}$

B) $\mathbf{W = p + \mathrm{\Delta}V}$

C) $\mathbf{W = p\mathrm{\Delta}V}$

D) $\mathbf{W =}$ $\frac{\mathbf{p}}{\mathbf{\mathrm{\Delta}V}}$

2 / 40

In the equation $\mathbf{W = p\mathrm{\Delta}V}$, the symbol $\mathbf{\mathrm{\Delta}V}$ represents:

A) Total volume of gas

B) Initial volume

C) Final volume

D) Change in volume

3 / 40

The SI unit of work done by a gas is:

A) Newton

B) Pascal

C) Watt

D) Joule

4 / 40

The SI unit of pressure in $\mathbf{W = p\mathrm{\Delta}V}$ is:

A) $\mathbf{Pa}$

B) bar

C) $\mathbf{atm}$

D) $\mathbf{N}$

5 / 40

A gas expands against a constant pressure. The work done by the gas is:

A) Infinite

B) Positive

C) Negative

D) Zero

6 / 40

If a gas is compressed at constant pressure, the work done by the gas is:

A) Positive

B) Maximum

C) Zero

D) Negative

7 / 40

A gas expands from $\mathbf{2\ m}^{\mathbf{3}}$ to $\mathbf{5\ m}^{\mathbf{3}}$ at a pressure of $\mathbf{1000\ Pa}$. The work done is:

A) $\mathbf{5000\ J}$

B) $\mathbf{2000\ J}$

C) $\mathbf{7000\ J}$

D) $\mathbf{3000\ J}$

8 / 40

A gas expands by $\mathbf{0.02\ m}^{\mathbf{3}}$ against a pressure of $\mathbf{5 \times}\mathbf{10}^{\mathbf{4}}\mathbf{\ Pa}$. Work done is:

A) $\mathbf{2500\ J}$

B) $\mathbf{500\ J}$

C) $\mathbf{1000\ J}$

D) $\mathbf{100\ J}$

9 / 40

If there is no change in volume of a gas, the work done is:

A) Minimum but not zero

B) Negative

C) Maximum

D) Zero

10 / 40

The work done by a gas during expansion represents:

A) Change in temperature only

B) Increase in mass of gas

C) Decrease in pressure only

D) Energy transferred by the gas to surroundings

11 / 40

The area under a pressure-volume graph represents:

A) Density

B) Internal energy only

C) Temperature

D) Work done

12 / 40

On a pressure-volume graph, constant pressure is represented by:

A) A horizontal line

B) A curved line

C) A circle

D) A vertical line

13 / 40

For a gas expanding at constant pressure, increasing the volume change will:

A) Decrease work done

B) Have no effect

C) Increase work done

D) Make work zero

14 / 40

If pressure is doubled while volume change remains constant, work done:

A) Becomes zero

B) Doubles

C) Becomes half

D) Remains unchanged

15 / 40

A gas expands from $\mathbf{1\ m}^{\mathbf{3}}$ to $\mathbf{4\ m}^{\mathbf{3}}$ at $\mathbf{(2000\ Pa)}$. The work done is:

A) $\mathbf{2000\ J}$

B) $\mathbf{4000\ J}$

C) $\mathbf{8000\ J}$

D) $\mathbf{6000\ J}$

16 / 40

Which condition is necessary for using $\mathbf{W = p\mathrm{\Delta}V}$?

A) Constant volume

B) Zero pressure

C) Constant temperature

D) Constant pressure

17 / 40

During expansion of a gas, the surroundings:

A) Receive work from the gas

B) Gain no energy

C) Stop moving

D) Do work on the gas

18 / 40

A gas does $\mathbf{500\ J}$ of work while expanding at constant pressure of $\mathbf{2500\ Pa}$. The change in volume is:

A) $\mathbf{2\ m}^{\mathbf{3}}$

B) $\mathbf{0.2\ m}^{\mathbf{3}}$

C) $\mathbf{0.1\ m}^{\mathbf{3}}$

D) $\mathbf{0.5\ m}^{\mathbf{3}}$

19 / 40

If a gas is compressed, the final volume is:

A) Greater than initial volume

B) Infinite

C) Less than initial volume

D) Equal to initial volume

20 / 40

The equation $\mathbf{W = p\mathrm{\Delta}V}$ is derived from:

A) Mass $\mathbf{\times}$ acceleration

B) Pressure $\mathbf{\times}$ temperature

C) Force $\mathbf{\times}$ displacement

D) Energy $\mathbf{\times}$ time

21 / 40

Pressure is defined as:

A) Force $\mathbf{\times}$ area

B) Volume per unit force

C) Force per unit area

D) Energy per unit volume

22 / 40

A gas expands from $\mathbf{3L}$ to $\mathbf{8L}$ at $\mathbf{2 \times}\mathbf{10}^{\mathbf{5\ }}\mathbf{Pa}$. The work done is:

A) $\mathbf{100\ J}$

B) $\mathbf{2000\ J}$

C) $\mathbf{500\ J}$

D) $\mathbf{1000\ J}$

23 / 40

Work done by a gas depends on:

A) Temperature only

B) Density only

C) Pressure and volume change

D) Mass only

24 / 40

A gas expands at constant pressure. Which statement is correct?

A) Gas transfers energy to surroundings

B) Energy is transferred from surroundings to gas as work

C) No energy transfer occurs

D) Gas loses all internal energy

25 / 40

If pressure is constant and volume increases three times more than before, work done becomes:

A) Three times greater

B) Unchanged

C) One-third

D) Zero

26 / 40

A piston moves outward because gas pressure pushes it. The gas is:

A) Expanding

B) Losing particles

C) Being compressed

D) At constant volume

27 / 40

The sign convention for work done by gas during expansion is usually:

A) Positive

B) Negative

C) Undefined

D) Zero

28 / 40

A gas has pressure $\mathbf{4 \times}\mathbf{10}^{\mathbf{4}}\mathbf{\ Pa}$ and expands by $\mathbf{0.5\ m}^{\mathbf{3}}$. Work done equals:

A) $\mathbf{8 \times}\mathbf{10}^{\mathbf{4}}\mathbf{\ J}$

B) $\mathbf{4 \times}\mathbf{10}^{\mathbf{5}}\mathbf{\ J}$

C) $\mathbf{2 \times}\mathbf{10}^{\mathbf{3}}\mathbf{\ J}$

D) $\mathbf{2 \times}\mathbf{10}^{\mathbf{4}}\mathbf{\ J}$

29 / 40

If a gas expands at zero pressure, work done is:

A) Infinite

B) Negative

C) Positive

D) Zero

30 / 40

The physical meaning of $\mathbf{p\mathrm{\Delta}V}$ is:

A) Temperature change

B) Mechanical work done during volume change

C) Molecular energy

D) Heat stored in gas

31 / 40

A gas expands at constant pressure from $\mathbf{10\ m}^{\mathbf{3}}$ to $\mathbf{12\ m}^{\mathbf{3}}$. If $\mathbf{p = 500\ Pa}$, work done is:

A) $\mathbf{1000\ J}$

B) $\mathbf{2000\ J}$

C) $\mathbf{5000\ J}$

D) $\mathbf{6000\ J}$

32 / 40

Which graph gives the work done during constant pressure expansion?

A) Area under $\mathbf{P - V}$ curve

B) Slope of $\mathbf{P - V}$ curve

C) Pressure-time graph

D) Temperature-volume graph

33 / 40

A negative value of work done by gas indicates:

A) Heating only

B) Constant volume

C) Compression

D) Expansion

34 / 40

The equation $\mathbf{W = p\mathrm{\Delta}V}$ is an application of:

A) Momentum law only

B) Conservation of charge

C) Newton’s third law only

D) Conservation of energy

35 / 40

A gas absorbs heat and expands at constant pressure. Some energy is used for:

A) Stopping collisions

B) Reducing mass

C) Decreasing molecular motion

D) Doing external work

36 / 40

The unit conversion needed when volume is given in liters is:

A) $\mathbf{1\ L =}\mathbf{1\ m}^{\mathbf{3}}$

B) $\mathbf{1\ L =}\mathbf{10}^{\mathbf{- 3}}\mathbf{\ m}^{\mathbf{3}}$

C) $\mathbf{1\ L =}\mathbf{10}^{\mathbf{3}}\mathbf{\ m}^{\mathbf{3}}$

D) $\mathbf{1\ L =}\mathbf{10}^{\mathbf{- 6}}\mathbf{\ }\mathbf{m}^{\mathbf{3}}$

37 / 40

The work done by gas at constant pressure is maximum when:

A) Pressure and expansion are large.

B) Volume change is zero.

C) Pressure is zero.

D) Gas is compressed slightly.

38 / 40

The work done by a gas increases if:

A) Pressure decreases and volume change decreases.

B) Volume remains constant.

C) Pressure becomes zero.

D) Pressure and volume change both increase.

39 / 40

If $\mathbf{W = 1000\ J}$ and $\mathbf{\mathrm{\Delta}V =}\mathbf{0.5\ m}^{\mathbf{3}}$, pressure is:

A) $\mathbf{1000\ Pa}$

B) $\mathbf{2000\ Pa}$

C) $\mathbf{5000\ Pa}$

D) $\mathbf{500\ Pa}$

40 / 40

The equation $\mathbf{W = p\mathrm{\Delta}V}$ shows that work done is:

A) Always negative

B) Independent of pressure

C) Independent of volume change

D) Directly proportional to pressure and volume change

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