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Density

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Question 27

A student determines the density of a block of modelling clay. They obtain the following measurements:

  • Length, l=4.8 cml = 4.8\text{ cm}l=4.8 cm
  • Width, w=3.2 cmw = 3.2\text{ cm}w=3.2 cm
  • Height, h=2.5 cmh = 2.5\text{ cm}h=2.5 cm
  • Weight of the block, W=0.64 NW = 0.64\text{ N}W=0.64 N
  • Initial volume of water in a measuring cylinder, V2=120 cm3V_2 = 120\text{ cm}^3V2​=120 cm3
  • New volume of water with the block of clay fully submerged, V3=156 cm3V_3 = 156\text{ cm}^3V3​=156 cm3
a.

(i) Calculate the volume V1V_1V1​ of the block of modelling clay using the equation V1=l×w×hV_1 = l \times w \times hV1​=l×w×h. (ii) Suggest a possible source of inaccuracy in measuring the dimensions of this block of modelling clay, and describe an improvement to the procedure to obtain more reliable measurements of these dimensions.

[3]
b.

Calculate a value ρ1\rho_1ρ1​ for the density of the modelling clay, using the equation:

ρ1=W×kV1 \rho_1 = \frac{W \times k}{V_1} ρ1​=V1​W×k​

where k=100 g/Nk = 100\text{ g/N}k=100 g/N. Include the unit in your final answer.

[2]
c.

(i) Describe how a student should read a measuring cylinder to obtain an accurate value for the volume of water. (ii) Calculate another value ρ2\rho_2ρ2​ for the density of the modelling clay, using the equation:

ρ2=W×kV3−V2 \rho_2 = \frac{W \times k}{V_3 - V_2} ρ2​=V3​−V2​W×k​

where k=100 g/Nk = 100\text{ g/N}k=100 g/N.

[4]
d.

Suggest which value, ρ1\rho_1ρ1​ or ρ2\rho_2ρ2​, is likely to be the more accurate value for the density of the modelling clay. Justify your answer.

[1]
Markscheme

Density Questions

  1. IGCSE
  2. /Physics
  3. /Density

169 exam-style questions on CIE IGCSE Physics Density, covering Density. Each one has a worked solution and a mark scheme showing where the marks go.

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