Define density as it is used in the context of solids and liquids, giving the equation and naming each symbol.
(Total for Question 1 is 1 mark)
2
State a typical value for atmospheric pressure at sea level and give its units.
(Total for Question 2 is 1 mark)
3
A small metal cube used in a school test has mass 0.48 kg and volume 60 cm3. Calculate its density in kg/m3.
(Total for Question 3 is 2 marks)
4
A cube of plastic has edge length 6.0 cm and density 950 kg/m3. Calculate the mass of the cube in grams. Show equation, substitution and final answer with units.
(Total for Question 4 is 2 marks)
5
Define pressure in a liquid at a depth and state the equation linking pressure, depth, fluid density and gravitational field strength, naming symbols.
(Total for Question 5 is 2 marks)
6
Ice of mass 0.25 kg at 0 degrees C is melted to water at 0 degrees C. The specific latent heat of fusion of ice is 3.34 x 105 J/kg. Calculate the energy required. Show equation, substitution and final answer with units.
(Total for Question 6 is 3 marks)
7
Using p = h ρ g, calculate how much the pressure increases per metre depth in freshwater (ρ = 1000 kg/m3). Give your answer in Pa per metre. Use g = 9.8 N/kg.
(Total for Question 7 is 2 marks)
8
A diver swims at a depth of 12 m in seawater with density 1025 kg/m3. Calculate the increase in pressure due to the water at that depth. Use g = 9.8 N/kg. Give your answer in Pa.
(Total for Question 8 is 3 marks)
9
Explain why the pressure at the base of a tall tank of mercury is greater than at the base of a tall tank of water of the same depth, using the p = h ρ g equation and particle ideas.
(Total for Question 9 is 3 marks)
10
A sealed container has two immiscible liquid layers of equal depth 0.20 m. The lower layer is oil with density 850 kg/m3 and the upper layer is water with density 1000 kg/m3. Calculate the pressure at the interface between the oil and water due to the oil alone. Use g = 9.8 N/kg. Give your answer in Pa.
(Total for Question 10 is 2 marks)
11
A block of aluminium of mass 270 g is heated, and its temperature rises from 20 degrees C to 80 degrees C. The specific heat capacity of aluminium is 900 J/kg degrees C. Calculate the energy required to heat the block. Show equation, substitution and final answer with units.
(Total for Question 11 is 3 marks)
12
A student uses 500 g of water at 20 degrees C and supplies 9,000 J of energy. Calculate the final temperature of the water. Use specific heat capacity of water as 4200 J/kg degrees C. Show equation, substitution and final answer with units.
(Total for Question 12 is 4 marks)
13
A kettle contains 0.35 kg of water at 100 degrees C and some of the water is converted to steam at 100 degrees C. If 4.6 x 105 J of energy is supplied to the kettle to boil water into steam, calculate the mass of water that becomes steam. Use specific latent heat of vaporisation L = 2.26 x 106 J/kg. Show equation, substitution and final answer with units.
(Total for Question 13 is 3 marks)
Mark scheme · 3.10 Density, Pressure in Liquids and Change of State
Question 1
B1 ρ = mass / volume, with ρ = density, mass = mass (kg) and volume = volume (m3) or equivalent units
Answer: ρ = mass / volume, where ρ is density, mass is mass and volume is volume
Question 2
B1 1.01 x 105 Pa or 101,325 Pa
Answer: 1.01 x 105 Pa (approximately 101,325 Pa)
Question 3
M1 convert 60 cm3 to m3 = 60 x 10-6 m3 or 6.0 x 10-5 m3
A1 mass = density x volume = 950 x 216e-6 = 0.2052 kg = 205.2 g cao
Answer: Mass = 205.2 g
Question 5
B1 p = h x ρ x g with p = pressure, h = depth, ρ = fluid density, g = gravitational field strength
B1 states that pressure increases with depth and with fluid density
Answer: p = h ρ g, where p is pressure, h depth, ρ fluid density and g gravitational field strength; pressure increases with depth and density
Question 6
M1 writes E = m L
M1 substitutes m = 0.25, L = 3.34 x 105 so E = 0.25 x 3.34 x 105
A1 E = 8.35 x 104 J cao
Answer: E = 8.35 x 104 J (83,500 J)
Question 7
M1 uses p/h = ρ g = 1000 x 9.8
A1 pressure increases by 9,800 Pa per metre cao
Answer: Pressure increases by 9,800 Pa per metre
Question 8
M1 writes p = h ρ g
M1 substitutes p = 12 x 1025 x 9.8
A1 p = 120,540 Pa (give or take rounding) cao
Answer: 1.21 x 105 Pa (120540 Pa)
Question 9
B1 states p = h ρ g and that h and g are same so difference is ρ
B1 mercury has higher density (more mass per unit volume) than water
B1 therefore weight of column above base is greater, so pressure at base is greater
Answer: Because mercury has a larger density, the term ρ is bigger so p = h ρ g is larger; a denser fluid means more mass in the same column and therefore more weight on the base
Question 10
M1 uses p = h ρ g with h = 0.20, ρ = 850, g = 9.8
A1 p = 0.20 x 850 x 9.8 = 1666 Pa (rounding acceptable) cao
Answer: Approximately 1.67 x 103 Pa (1666 Pa)
Question 11
M1 writes E = m c DeltaT
M1 substitutes m = 0.270 kg, c = 900, DeltaT = 60 so E = 0.270 x 900 x 60
A1 E = 14,580 J cao with units
Answer: E = 1.46 x 104 J (14,580 J)
Question 12
M1 writes E = m c DeltaT
M1 substitutes E = 9000, m = 0.500 kg, c = 4200 so 9000 = 0.500 x 4200 x DeltaT
M1 rearranges to DeltaT = 9000 / (0.500 x 4200)
A1 DeltaT = 4.29 degrees C so final temperature = 24.29 degrees C cao
Answer: Final temperature = about 24.3 degrees C
Question 13
M1 writes E = m L and rearranges to m = E / L
M1 substitutes m = 4.6 x 105 / 2.26 x 106
A1 m = 0.2035 kg (allow awrt 0.204 kg) cao
Answer: Approximately 0.204 kg of water becomes steam