GCSE_AQA_Energy_Stores_and_Changes _QP.pdf

Page 1 of 19 Catalyst TutorsEnergy Stores and Changes Questions Name: ________________________ Class: ________________________ Date: ________________________   Time: 76 minutes Marks: 75 marks Comments:   theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 2 of 1...

Page 1 of 19 Catalyst TutorsEnergy Stores and Changes Questions Name: ________________________ Class: ________________________ Date: ________________________   Time: 76 minutes Marks: 75 marks Comments:   theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 2 of 19 Catalyst TutorsA student did an experiment to calculate her power. The diagram below shows how she obtained the measurements needed. The student first weighed herself and then ran up a flight of stairs. A second student timed how long it took her to go from the bottom to the top of the stairs. The height of the stairs was also measured.   1 (a)     Complete the following sentence. To run up the stairs the student must do work against the force of ___________ . (1) (b)     The student did 2240 J of work going from the bottom of the stairs to the top of the stairs. The student took 2.8 seconds to run up the stairs. (i)      Calculate the power the student developed when running up the stairs. ______________________________________________________________ ______________________________________________________________ Power = ___________ W (2) (ii)     How much gravitational potential energy did the student gain in going from the bottom to the top of the stairs? Tick ( ✔) one box.   much more than 2240 J 2240 J much less than 2240 J (1) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 3 of 19 Catalyst Tutors(c)     Another four students did the same experiment. The measurements taken and the calculated values for power are given in the table.   Student Weight in newtons Time taken in seconds Power in watts A 285 3.8 240 B 360 2.4 480 C 600 3.4 560 D 725 4.0 580 (i)      To make a fair comparison of their powers the students kept one variable in the experiment constant. What variable did the students keep constant? ______________________________________________________________ (1) (ii)     From the data in the table a student wrote the following conclusion. 'The greater the weight of the student the greater the power developed.' Suggest why this conclusion may not be true for a larger group of students. ______________________________________________________________ ______________________________________________________________ (1) (Total 6 marks) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 4 of 19 Catalyst TutorsThe image below shows a student before and after a bungee jump. The bungee cord has an unstretched length of 20 m.   2 (a)     For safety reasons, it is important that the bungee cord used is appropriate for the student’s weight. Give two reasons why. 1. _________________________________________________________________ ___________________________________________________________________ 2. _________________________________________________________________ ___________________________________________________________________ (2) (b)     The student jumps off the bridge. Complete the sentences to describe the energy transfers. Use answers from the box.   elastic potential        gravitational potential        kinetic        sound        thermal theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 5 of 19 Catalyst TutorsBefore the student jumps from the bridge he has a store of _____________________ energy. When he is falling, the student's store of _____________________ energy increases. When the bungee cord is stretched, the cord stores energy as _____________________ energy. (3) (c)     At the lowest point in the jump when the student is stationary, the extension of the bungee cord is 35 metres. The bungee cord behaves like a spring with a spring constant of 40 N / m. Calculate the energy stored in the stretched bungee cord. Use the correct equation from the Physics Equations Sheet. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ Energy = __________________________ J (2) (Total 7 marks) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 6 of 19 Catalyst TutorsThe diagram shows a tennis ball thrown vertically into the air.   At position C, the ball has just left the tennis player's hand at a speed of 5.0 m/s The tennis ball has a mass of 0.058 kg 3 (a)     Write down the equation that links kinetic energy, mass and speed. ___________________________________________________________________ (1) (b)     Calculate the kinetic energy of the tennis ball at position C. ___________________________________________________________________ ___________________________________________________________________ Kinetic energy = ____________________ J (2) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 7 of 19 Catalyst Tutors(c)     At position A the tennis ball is at maximum height. What is the gravitational potential energy of the tennis ball at position A? Ignore the effect of air resistance. ___________________________________________________________________ (1) At position B the tennis ball has 0.38 J of gravitational potential energy. (d)     Write down the equation that links gravitational field strength, gravitational potential energy, height and mass. ___________________________________________________________________ (1) (e)     Calculate the height of the tennis ball above the tennis player's hand when at position B. gravitational field strength = 9.8 N/kg ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ Height = ____________________ m (3) (Total 8 marks) 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. 4 theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 8 of 19 Catalyst Tutors(a)     (i)     Name the useful energy output from the electric motor. ______________________________________________________________ (1) (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? ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ (2) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 9 of 19 Catalyst Tutors  (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) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 10 of 19 Catalyst TutorsThe image shows a battery-powered drone.   5 (a)     Complete the sentences. Choose the answers from the box.     chemical elastic potential gravitational potential kinetic nuclear As the drone accelerates upwards its _________________________________________ energy increases and its _________________________________________ energy increases. The _________________________________________ energy store of the battery decreases. (3) (b)     In the USA, drones are not allowed to be flown too high above the ground. Suggest one possible risk of flying a drone too high above the ground. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ (2) (c)     Write down the equation that links energy transferred, power and time. ___________________________________________________________________ (1) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 11 of 19 Catalyst Tutors(d)     The drone can fly for 25 minutes before the battery needs recharging. The power output of the battery is 65.0 W Calculate the maximum energy stored by the battery. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ Maximum energy = ____________________ joules (3) (Total 8 marks) The miners working in a salt mine use smooth wooden slides to move quickly from one level to another.   6 (a)     A miner of mass 90 kg travels down the slide. Calculate the change in gravitational potential energy of the miner when he moves 15 m vertically downwards.   gravitational field strength = 10 N/kg Show clearly how you work out your answer. ___________________________________________________________________ ___________________________________________________________________ Change in gravitational potential energy = _________________________ J (2) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 12 of 19 Catalyst Tutors(b)     Calculate the maximum possible speed that the miner could reach at the bottom of the slide. Show clearly how you work out your answer. Give your answer to an appropriate number of significant figures. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ Maximum possible speed = _________________________ m/s (3) (c)     The speed of the miner at the bottom of the slide is much less than the calculated maximum possible speed. Explain why. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ (3) (Total 8 marks) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 13 of 19 Catalyst Tutors(a)     Draw one line from each velocity−time graph to the statement describing the motion shown by the graph.   (2) 7 (b)     Use the correct answer from the box to complete the sentence.   energy momentum speed The velocity of an object includes both the _________________________ of the object and the direction the object is moving. (1) (c)     At the start of a race, a horse accelerates from a velocity of 0 m/s to a velocity of 9 m/s in 4 seconds. (i)      Calculate the acceleration of the horse. ______________________________________________________________ ______________________________________________________________ Acceleration = ______________________ m/s 2 (2) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 14 of 19 Catalyst Tutors(ii)     When the horse accelerates, what, if anything, happens to the air resistance acting against the horse? Tick ( ) one box.   The air resistance decreases The air resistance is constant The air resistance increases (1) (d)     A horse and a pony walk across a field at the same constant speed. The horse has 4000 joules of kinetic energy. The pony is half the mass of the horse. What is the kinetic energy of the pony? Draw a ring around the correct answer   2000 J 4000 J 8000 J Give a reason for your answer. ___________________________________________________________________ ___________________________________________________________________ (2) (Total 8 marks) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 15 of 19 Catalyst TutorsThe figure below shows a student before and after a bungee jump. The bungee cord has an unstretched length of 20.0 m.   The mass of the student is 50.0 kg. The gravitational field strength is 9.8 N / kg. (a)     Write down the equation which links gravitational field strength, gravitational potential energy, height and mass. ___________________________________________________________________ (1) 8 (b)     Calculate the change in gravitational potential energy from the position where the student jumps to the point 20.0 m below. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ Change in gravitational potential energy = _____________ J (2) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 16 of 19 Catalyst Tutors(c)     80% of this change in gravitational potential energy has been transferred to the student’s kinetic energy store. How much has the student’s kinetic energy store increased after falling 20.0 m? Kinetic energy gained = ________________________ J (1) (d)     Calculate the speed of the student after falling 20.0 m. Give your answer to two significant figures. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ Speed = __________________________ m / s (4) (e)     At the lowest point in the jump, the energy stored by the stretched bungee cord is 24.5 kJ. The bungee cord behaves like a spring. Calculate the spring constant of the bungee cord. Use the correct equation from the Physics Equation Sheet. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ Spring constant = ________________________ N / m (3) (Total 11 marks) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 17 of 19 Catalyst Tutors(a)      Figure 1 shows the forces acting on a model air-powered rocket just after it has been launched vertically upwards.   9 (i)      How does the velocity of the rocket change as the rocket moves upwards ? ______________________________________________________________ Give a reason for your answer. ______________________________________________________________ ______________________________________________________________ (2) (ii)     The velocity of the rocket is not the same as the speed of the rocket. What is the difference between the velocity of an object and the speed of an object? ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ (1) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 18 of 19 Catalyst Tutors(b)     The speed of the rocket just after being launched is 12 m / s. The mass of the rocket is 0.05 kg. (i)      Calculate the kinetic energy of the rocket just after being launched. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ Kinetic energy = _____________________ J (2) (ii)     As the rocket moves upwards, it gains gravitational potential energy. State the maximum gravitational potential energy gained by the rocket. Ignore the effect of air resistance. Maximum gravitational potential energy = _____________________ J (1) (iii)    Calculate the maximum height the rocket will reach. Ignore the effect of air resistance. Gravitational field strength = 10 N/kg. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ Maximum height = _____________________ m (2) (iv)     Figure 2 shows four velocity−time graphs.   theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor Page 19 of 19 Catalyst TutorsTaking air resistance into account, which graph, A, B, C or D, shows how the velocity of the rocket changes as it falls from the maximum height it reached until it just hits the ground?   Write the correct answer in the box. (1) (c)     The rocket can be launched at different angles to the horizontal. The horizontal distance the rocket travels is called the range. Figure 3 shows the paths taken by the rocket when launched at different angles. Air resistance has been ignored.   What pattern links the angle at which the rocket is launched and the range of the rocket? ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ (2) (Total 11 marks) theonlinephysicstutor.com @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor