Heat

Question 13:Photograph 3 shows a bamboo steamer. Amin receives an order from a supermarket to supply 400 steamed buns per day. Suggest and explain the design of the steamer needed. The steamer should be durable, and able to prepare a large quantity of steamed buns in a short time. Answer: Question 14:Khairi orders a cup … Read more

Question 11:An electric kettle is filled with 500 g of water at 30°C. The power of the heating element of the kettle is 0.8 kW. Assume that all heat from the heating element is transferred to the water. [Specific heat capacity of water = 4 200 J kg–1 °C–1.](a) Calculate:(i) heat energy needed to increase … Read more

Question 9:An air bubble is trapped under a leaf floating on the water surface of a lake. Th e volume of the air bubble is 3.6 cm3 when the temperature is 20°C.(a) What is the volume of the air bubble when the water temperature rises to 38°C?(b) State three assumptions that need to be made … Read more

Question 7:Photograph 2 shows the power rating label of an electric kettle.(a) What is the maximum power of this electric kettle?(b) Calculate the time taken by this kettle to change 0.5 kg of boiling water at 100°C into steam at 100°C when the kettle operates at maximum power. [Specific latent heat of vaporisation of water … Read more

Question 4:(a) Define specific latent heat.(b) Th e mass of a melting ice cube reduces by 0.68 kg. What is the amount of heat absorbed from the surrounding by the ice cube?[Specific latent heat of fusion of ice = 3.34 × 105 J kg–1]Answer:(a) Specific latent heat is the quantity of heat absorbed or released … Read more

Question 1:Photograph 1 shows a steam injector machine which can inject steam into water in a container.(a) What is the meaning of latent heat?(b) Explain how water in the container is heated by steam injected into it.(c) What is the advantage of heating water using the injection of steam?Answer:(a) Latent heat is the heat that … Read more

Question 4:Pressure in a gas cylinder is 175 kPa at a temperature of 27°C. Heat from a nearby furnace causes the gas pressure to increase to 300 kPa. What is the temperature of the gas inside the cylinder?Answer:\begin{aligned} & P_1=175 \mathrm{kPa} \\ & P_2=300 \mathrm{kPa} \\ & T_1=27+273=300 \mathrm{~K} \\ & T_2=? \end{aligned}Gay-Lussac’s Law formula: … Read more

Question 1:State the physical quantities that are constant in Boyle’s Law, Charles’ Law and Gay-Lussac’s Law.Answer: Question 2:A syringe contains 50 cm3 of air at a pressure of 110 kPa. Th e end of the syringe is closed and its piston slowly pushed until the volume of air becomes 20 cm3. What is the pressure … Read more

Question 1:Figure 4.23 shows an electric steamer. Explain how the fish is heated.Answer:– Water has large specific latent heat of vaporization.– When the steam condenses on the fish, the specific latent heat is released directly to the fish.– This enable the fish to be cooked faster. Question 2:What is the amount of heat released when … Read more

Question 1:What is the difference between heat capacity and specific heat capacity?Answer: Question 2:How much heat energy is needed to increase the temperature of a 0.2 kg mass of gold by 10°C? [Given the value of specific heat capacity of gold is 300 J kg–1 °C–1] Answer: \begin{aligned} Q & =m c \theta \\ & … Read more