Mass, Weight & Density (Cambridge (CIE) IGCSE Physics)

Exam Questions

3 hours45 questions

1a4 marks

A student is determining the density of wood by two methods.

He is using the wooden rod shown in Fig. 1.1.

Method 1

The dimensions of the wooden rod are shown full size in Fig. 1.2.

(i) Measure the length l and the diameter d of the wooden rod in Fig. 1.2.

l = ......................................................... cm

d = ......................................................... cm

[2]

(ii) Suggest an accurate method for measuring the diameter of the wooden rod in this experiment.

List any additional apparatus that might be required and briefly describe how you would determine the diameter.

You may draw a diagram if it helps to explain your answer.

[2]

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1b2 marks

The student uses a balance to measure the mass m of the wooden rod as shown in Fig. 1.3.

Record the mass m of the rod.

m = ............................................................g

Calculate a value ρ₁ for the density of the wooden rod. Use the values l = 4.5 cm and d = 2.0 cm, the value of the mass, and the equation $ρ_{1} = \frac{4 m}{π d^{2} l}$ . Include a suitable unit.

ρ₁ = ........................................................

How did you do?

1c1 mark

Method 2

The student pours water into a measuring cylinder as shown in Fig. 1.4. He then floats the wooden rod in the water as shown in Fig. 1.5.

Record the reading V₁ in cm³ of the water level in the measuring cylinder as shown in Fig. 1.4.

V₁ = ........................................................cm³

Record the new reading V₂ in cm³of the water level in the measuring cylinder with the rod floating in the water as shown in Fig. 1.5.

V₂ = ........................................................cm³

[1]

1d2 marks

The student removes the rod and lowers a piece of modelling clay into the water as shown in Fig. 1.6.

He then hooks the rod to the modelling clay and lowers them into the water as shown in Fig. 1.7.

He records the new reading V₃ of the water level in the measuring cylinder with the modelling clay.

He records the reading V₄ of the water level in the measuring cylinder with the modelling clay and rod.

V₃ = 164 cm³

V₄ = 178 cm³

Calculate another value ρ₂ for the density of the wooden rod. Use the values from (c) and (d) and the equation $ρ_{2} = \frac{V_{2} - V_{1}}{V_{4} - V_{3}} \times k$ where k = 1.0 g/cm³.

ρ₂ = ........................................................

How did you do?

1e1 mark

On Fig. 1.8, draw an arrow showing the correct line of sight for reading the volume of water in the measuring cylinder.

How did you do?

1f1 mark

Suggest a possible source of inaccuracy in Method 2, even if it was carried out carefully.

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2a2 marks

A student is determining the density of modelling clay.

He is using the block shown in Fig. 1.1 and Fig. 1.2.

(i) Measure the dimensions of the block of modelling clay, as shown in Fig. 1.1 and Fig. 1.2.

length $l$ = ........................................................ cm

width $w$ = ........................................................ cm

height $h$ = ........................................................ cm

[1]

(ii) Calculate the volume V₁ of the block, using your measurements from (a)(i) and the following equation:

$V_{1} = l \times w \times h$

$V_{1}$ = .................................................. cm³ [1]

How did you do?

2b2 marks

Suggest a possible source of inaccuracy in measuring the dimensions of the block and describe an improvement to the procedure that will produce more reliable measurements of the block.

2c1 mark

The student suspends the piece of modelling clay from a forcemeter, as shown in Fig. 1.3.

Record the weight W in Newtons, N, of the block of modelling clay shown in Fig. 1.3.

W = ..................................................... N

2d2 marks

Calculate a value ρ₁ for the density of the modelling clay, using your results from (a)(ii) and (c) and the following equation:

$ρ_{1} = \frac{W \times k}{V_{1}}$

Where k = 100 g/N.

ρ₁ = .........................................................

How did you do?

2e2 marks

The student pours some water into a measuring cylinder, as shown in Fig. 1.4.

(i) Record the volume V₂ of the water in the measuring cylinder shown in Fig. 1.4.

V₂ = .................................................. cm³ [1]

(ii) Describe how a measuring cylinder is read to obtain an accurate value for the volume of water. You may draw a diagram to help you.

[1]

2f2 marks

The student lowers the modelling clay into the water, as shown in Fig. 1.5.

(i) Record the new reading V₃ of the measuring cylinder Fig. 1.5, with the block of modelling clay in the water.

V₃ = ....................................................... cm³

Calculate another value ρ₂for the density of modelling clay, using your value for V₃, your readings from (c) and (e)(i) and the equation:

$ρ_{2} = \frac{W \times k}{(V_{3} - V_{2})}$

where k = 100 g/N.

ρ₂ = ..............................................................

[1]

(ii) Suggest which of ρ₁ or ρ₂ is likely to be the more accurate value for the density of the modelling clay.

Justify your answer by referring to the procedure.

[1]

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