Density 1.pdf

# H.w. Pg:85-87 3.1 Density 10/7/24 1) Pinewood 0.41 g/cm³ Polycarbonate 1.2g/cm³ Polyethene 0.95 g/cm³ Water 1.0g/cm³ a) Which of these materials has the lowest density? Ans: Pinewood bi) Which of these materials will sink in water? Ans: Polycarbonate bii...

# H.w. Pg:85-87 3.1 Density 10/7/24 1) Pinewood 0.41 g/cm³ Polycarbonate 1.2g/cm³ Polyethene 0.95 g/cm³ Water 1.0g/cm³ a) Which of these materials has the lowest density? Ans: Pinewood bi) Which of these materials will sink in water? Ans: Polycarbonate bii) Explain why the material will sink in water? Ans: Because the density of polycarbonate is 1.2g/cm³, which is higher than 1.0g/cm³. 2a) Equation for density Density = Mass / Volume 2b) A block of aluminum has a volume of 5.0cm³ and a mass of 13.5g. Calculate the density of the aluminum. Give your answer in g/cm³. Ans: Density = 13.5g / 5.0cm³ = 2.7 g/cm³ 2c) Explain whether the block of aluminum will float or sink in water? Ans: It will sink because the density of aluminum is greater than the density of water. 3a) Calculate the volume of the block of wood Ans: V= l x w x h = 6 x 4 x 3 = 72cm³ 3b) The block of wood has a mass of 54g. Calculate the density of the wood? Density = 54g / 72cm³ = 0.75kg/cm³ 3c) Explain whether the block of wood will float or sink? Ans: Since the density of the wood is less than the density of water, it will float. 4) Sea water is placed in a tank. The volume of the sea water is 10m³. The mass of the sea water is 10,300kg a) Calculate the density of seawater. Ans: Density = 10,300kg / 10m³ = 1030 kg/m³ b) Pure water has a density of 1000kg/m³. Explain what will happen to a block of material with a density of 1020kg/m³ when placed into: i) Sea water Ans: Density of block=1020kg/m³. Density of sea water: 1030kg/m³. Since, the density of the block is less than the density of sea water, it will float in sea water. ii) Pure water Ans: Density of block = 1020kg/m³. Density of pure water = 1000kg/m³. Since, the density of the block is greater than the density of pure water, it will sink in pure water. 5) Copper has a density of 8.96g/cm³. a) Calculate the mass of copper that has a volume of 20cm³. Mass= Density x Volume = 8.96 x 20cm³ = 179.2g b) Calculate the volume of copper that has a mass of 4.5g. Ans: Volume= Mass / Density = 4.5g / 8.96 g/cm³ = 0.502cm³ 6a) Calculate the volume of the toy car. Ans: 78-50 = 28cm³ 6b) The toy car has a mass of 84g. Calculate the density of the toy car. Ans: Density: 84g / 28cm³ = 3g/cm³ (c) The toy car is made from steel and plastic. Steel has a density of 7.8g/cm³. Suggest 2 reasons for the difference between this value and the density you calculated in part b. Reason 1: The toy car is made from both steel and plastic and plastic generally has a lower density than steel, which could affect the overall density. Reason 2: The toy car might have air pockets or other materials inside that could affect it's density. # Self made notes Density 10/7/24 & Pr 'ban mar bd h hdl Hor ra a Calculating Volume: • Hollow - Space filled with air inside them. • If the shape of the materials irregular, we can work out the volume using the displacement method. The object is placed into a measuring cylinder of water. The difference between the volume of original water and the new rise of the volume of water is the volume of the object. A rock - Irregular shape Placed into a measuring cylinder 40cm³ Water rises to the 56cm³ mark Volume = 56-40 = 16cm³ # Self-made notes *Grases have lower density than liquids or solids because the particles in a gas are far apart. * Materials with the highest density are all solids. * For elements, density usually increases as the atomic number increases. Example: Osmium, Atomic Number: 76 is more dense than iron, atomic number=26. * Highest density in Universe, Collapsed star. Forces in collapsed stars are large that the atoms are compressed into very small pieces. Material: Neutronium, Density=100,000,000,000. * Mass = Amount of material/matter in an object, it's what makes things heavy or light. *Density is the mass per unit volume of a substance. *Volume Is the amount of space an object takes up. It's measured in cubic centimeters. (cm³) # 4.1 & 4.2 Self-made notes | yourself WS & Pr All bar Pammar Shobd. Baghd agrat Questi he * DH2O=1000kg/m³ or 1001 g/cm³ If an object has a density less than 1 g/cm³ it will float, if more it will sink. * DFE = 7870 kg/m³ * Dair = 1.29 kg/m³ *m↑ d↑ * If mass pemains constant and the volume increases, the density will decrease. * If volume decreases, density increases. * If the volume remains constant and the mass increases the density will increase. If the mass decreases, density decreases. * Not all solids have a higher density than liquid, which is ice made up of liquid. Dice=917 kg/m³ # Self-made notes * Ice will float. * Objects that are less than water will float on top and heavy objects will sink because it has a higher density than water. 1) Warm air and cold air which has the lower and greatest density? Ans: When the air is warm, the gas particles they move apart and expand. If we have the same amount of mass over a larger volume, density will decrease (V↑D↓) If we take away thermal energy from air molecules they contract, they get closer. Even though the mass is the same volume it will decrease and density will increase (V↓ D↑) As cold air has higher density it will sink and warm air will rise. # Photosy.. 2 Jonic bonds and stur, 3 Density 4.1 84.2 yourself 15 & Pr All bar ammar Shobd Baghe agra Quest he 17/7/24 Density= mass of water + mass of v.o / Vof water + Vof v.o = = 4x10 / 18 = 2/5 2kg vegetable oil Water 7ug * Density less, float * Density high, sink 1) What is Heat? Ans: Heat is a form of energy. It is the energy that moves from one object to another because of a difference in temperature. 2)What is Temperature? Ans: It is the measure of how hot op cold something is. It tells us how much thermal energy an object has. 3) Difference between heat and temperatur e Ans: The difference between heat and temperature is, heat is the energy moving between objects and temperature is a measure of how hot or cold an object is. # Self-made notes Density • Gases and liquids: Grases are less dense than liquids due to particle spacing. • Water is denser than air, so rain falls. The difference causes gas bubbles to pise in fizzy drinks. Fizzy drinks have co₂ gas with a low density. • Grases of different density: •Grases are less dense than liquid and solid. • Helium balloons float because helium is less dense than air. • Hydrogen is lighter but explosive. • Solids & liquids are hard to compress; gases are easy to compress. Compressing gas increases density; expanding gas decreases density. • Heating gas makes it expand, reducing density, which explains hot air balloons floating.