The rollercoaster car is raised a vertical distance of 35 m to point A by a motor in 45 seconds

Transcription

1 1 The figure below shows a rollercoaster. The rollercoaster car is raised a vertical distance of 35 m to point A by a motor in 45 seconds. The mass of the rollercoaster is 600 kg. The motor has a power rating of W. (a) Calculate the percentage efficiency of the motor. Gravitational field strength = 9.8 N / kg. Efficiency =... % (5) Page 1 of 24

2 (b) The rollercoaster rolls from point A to point B, a drop of 35 m. Calculate the speed of the roller coaster at point B. Assume that the decrease in potential energy store is equal to the increase in kinetic energy store. Speed at point B =... m / s (6) (Total 11 marks) Page 2 of 24

3 2 Figure 1 shows a battery operated remote control car. Figure 1 Brandon Bolin/iStock/Thinkstock (a) The car s battery contains a store of energy. As the car moves, energy from one store is transferred to another store. Describe how different stores of energy change as the car moves. (b) The car has a top speed of 12 m / s and a mass of 800 g. Write down the equation that links kinetic energy, mass and speed. Equation... (1) (c) Calculate the maximum kinetic energy of the car. Maximum kinetic energy =... J Page 3 of 24

4 (d) Explain why having a more efficient motor increases the top speed of the car. Page 4 of 24

5 (e) Figure 2 shows an electric car being charged. Figure 2 A driver wishes to buy a new car. By Alan Trotter Electric Car Charging [CC-BY-2.0]via Flickr The table below gives some data about an electric car and one with a petrol engine. Electric car Petrol engine car Cost ( ) Running cost per year ( ) Average lifetime (years) Which car would be the most economic over its 12 year lifetime? Use data from the table above to support your answer. You should include the difference in cost in your answer. Page 5 of 24

6 (4) (Total 11 marks) 3 A student investigated the change in temperature when oils of different specific heat capacities were heated. She set up the apparatus shown in the figure below. This is the method used. 1. Put 25 g of oil into a boiling tube. 2. Pour 100 ml of water into a beaker and heat it with a Bunsen burner. 3. When the water is boiling, put the boiling tube into the beaker. 4. When the temperature of the oil reaches 30 C, heat for a further 30 seconds and record the rise in temperature. 5. Repeat with different oils. 6. Repeat the whole investigation. (a) Name two pieces of apparatus the student used that are not shown in the figure above Page 6 of 24

7 (b) What are the independent and dependent variables in the student s investigation? Independent... Dependent... (c) Give two safety precautions the student should have taken (d) Suggest one improvement to the student s method. Page 7 of 24

8 (e) The table below shows the student s results. Temperature rise in C Type of oil Mean Castor oil Linseed oil Mineral oil Olive oil Sesame oil Calculate the mean temperature rise for olive oil. Give your answer to two significant figures. Mean temperature rise =... C Page 8 of 24

9 (f) The mean change in temperature of the castor oil is 20 C The specific heat capacity of castor oil is J / kg C The mass of oil used is kg Calculate the change in thermal energy of the castor oil the student used. Use the correct equation from the Physics Equations Sheet. Select the correct unit from the box. joule newton volt Change in thermal energy =... C Unit =... C (3) (Total 13 marks) 4 An old house has a cast iron radiator. The radiator has hot water inside it. Photograph supplied by PhotoObjects.net/Thinkstock (a) The table shows how the power output of the radiator varies with the temperature difference between the hot water and the air temperature of the room. Page 9 of 24

10 Temperature difference in C Power output in W (i) Describe fully the relationship between temperature difference and power output. (1) (ii) The house owner wants to reduce their heating bills. Use the data in the table to advise the house owner. (1) (b) The air in a room is at a temperature of 12 C. The house owner switches the heating on until the temperature reaches 22 C. The amount of energy needed to raise the temperature of the air to 22 C is J. The mass of air in the room is 58 kg. Calculate the specific heat capacity of air and give the unit. Use the correct equation from the Physics Equations Sheet. Show clearly how you work out your answer Specific heat capacity =... (3) (Total 5 marks) Page 10 of 24

11 5 Modern kitchens can be fitted with a device that immediately supplies water at a temperature of 93 C. A tank that stores very hot water is fitted under the sink so that hot water is always available. The infrared radiation shield and the vacuum reduce the energy transfer to the surroundings. (a) Which two methods of energy transfer does the vacuum prevent? Method 1... Method 2... (b) The infrared radiation shield is made of shiny metal. Why does the shiny metal reduce energy transfer? (1) Page 11 of 24

12 (c) When the hot water tank is filled with water, the immersion heater can heat the water from a temperature of 15 C to 93 C in 10 minutes. The energy transferred to the water is joules. The specific heat capacity of water is 4200 J/kg C. Calculate the mass of water needed to fill the hot water tank. Use the correct equation from the Physics Equations Sheet. Show clearly how you work out your answer. Mass =... kg (3) (d) When hot water is not needed the immersion heater has a power input of 10 W. The energy is used to maintain the 93 C temperature in the hot water tank. How much energy, in joules, does the immersion heater transfer in 30 minutes when the power input is 10 W? Use the correct equation from the Physics Equations Sheet. Show clearly how you work out your answer. Energy =... J Page 12 of 24

13 (e) The manufacturer of the device made the following claim: When people use conventional electric kettles, they always boil more water than they actually need. This system makes sure you only heat the water you need. Suggest one other advantage of using the device compared to using a conventional electric kettle. (1) (Total 9 marks) 6 A student investigated the specific heat capacity of metals. (a) Describe an experiment the student could do to measure the specific heat capacity of a metal. (6) Page 13 of 24

14 (b) The student calculated the specific heat capacity of four metals. The table below shows the student s results. Metal Mass of material in kg Time in minutes Temperature change in C Change in thermal energy in J Calculated specific heat capacity of material in J / kg C Aluminium Brass Copper Steel Use data from the table above to calculate the temperature change for copper. Use the correct equation from the Physics Equation Sheet. Temperature change =... C (3) (c) What is the independent variable in the student s investigation? Tick one box. Mass of material Power used Time in minutes Type of material (1) Page 14 of 24

15 (d) The student calculated the specific heat capacity of aluminium to be 2390 J / kg C. The true specific heat capacity of aluminium is 900 J / kg C. Suggest why the student s result for aluminium is different from the true value. (e) The teacher suggested that putting bubble wrap round the metal block would change the results. How would using bubble wrap change the results? Give a reason for your answer. (Total 14 marks) 7 (a) Figure 1 shows a solar panel. Solar panels can be fitted to house roofs and used to heat water for domestic hot water systems. Page 15 of 24

16 Use Figure 1 to explain how the design of the water pipe increases the rate of energy transfer from the Sun to the water (3) (b) Figure 2 shows a different method of heating water called a ground source heat pump. Two holes are drilled into the ground and fitted with pipes. Warm water is pumped up one pipe and waste water is returned to the ground through the other pipe. In the house, energy is transferred from the warm water by a heat exchanger. (i) Suggest one advantage of using this method of heating water rather than using solar panels. (1) Page 16 of 24

17 (ii) A leaflet about a ground source heat pump states: Ground source heat pumps are % efficient. For each joule of mains electrical energy the pumps use, they transfer three to four times more energy from the water. Two students read the leaflet. Student A says, It is incorrect to say that a device is % efficient. Student B says, The statement is correct. Both conclusions could be considered to be correct. Explain why. Student A s conclusion... Student B s conclusion... (4) Page 17 of 24

18 (iii) Domestic water enters the heat exchanger at a temperature of 7.0 C and leaves the heat exchanger at a temperature of 55 C. Each day joules of energy are supplied to the water passing through the heat exchanger. Calculate the mass of water that can be heated each day. Choose the correct equation from the Physics Equations Sheet. Specific heat capacity of water = 4200 J / kg C. Give your answer to 2 significant figures. Mass of water =... kg (4) (Total 12 marks) 8 A student uses an electric motor to lift a load. In the motor, the electrical energy is transferred into other types of energy. Some of this energy is useful and the rest of the energy is wasted. (a) (i) Name the useful energy output from the electric motor.... (1) Page 18 of 24

19 (ii) What eventually happens to the wasted energy? (1) (b) The graph shows the input energy the motor needs to lift different loads by one metre. What can you conclude from the graph about the relationship between the load lifted and the input energy needed? Page 19 of 24

20 (c) A shop uses escalators to lift customers to different floor levels. The escalators use electric motors. When the shop is not busy some escalators are turned off. A sign tells the customers that the escalators are turned off to save energy. (i) Each escalator has one motor with an average power of 4000 W. The motor is turned on for an average of 8 hours each day, 6 days each week. Electricity costs 15 pence per kilowatt-hour. Calculate the cost of the electricity used in an average week to run one escalator. Show clearly how you work out your answer Cost =... pence (3) (ii) Give one environmental advantage to turning off electrical appliances when they are not being used (1) (Total 8 marks) Page 20 of 24

21 9 When a gun is fired, a very large force acts on the bullet for a very short time. The change in momentum of the bullet is given by the following relationship: force (N) time(s) = change in momentum (kg m/s) (a) An average force of 4000 newton acts for 0.01 seconds on a bullet of mass 50g. Calculate the speed of the bullet. (Show your working.) Answer... m/s (4) (b) The bullet is fired horizontally. In the short time it takes for the bullet to reach its target, its horizontal speed has fallen to 80% of its initial speed. (i) Explain why the speed of the bullet decreases so quickly. (ii) Calculate the percentage of its original kinetic energy the bullet still has when it reaches its target. (Show your working.) (4) (Total 10 marks) Page 21 of 24

22 10 Solar panels can heat water for use in a home. Figure 1 shows a solar panel on the roof of a house. (a) The solar panel is designed to transfer as much energy to the water as possible. (i) Draw a ring around the correct answer to complete the sentence. The solar panel is black to increase energy transferred to the water by conduction. convection. infrared radiation. (1) (ii) Draw a ring around the correct answer to complete the sentence. Solar panels usually have a large surface area so that more energy can be absorbed. emitted. reflected. (1) Page 22 of 24

23 (b) Figure 2 shows the hours of sunlight each month for one year in France and in the UK. Solar panels are used more in France than in the UK. Use Figure 2 to explain why. Page 23 of 24

24 (c) The solar panel heats 200 kg of water each day. On one day it increases the temperature of the water by 50 C. The specific heat capacity of water is 4200 J / kg C. Calculate the energy needed to increase the temperature of 200 kg of water by 50 C. Use the correct equation from the Physics Equations Sheet. Tick ( ) the correct unit. Energy =... joules seconds watts Tick ( ) (3) (Total 7 marks) Page 24 of 24