Changes in Energy 1 QP.pdf

Q1.The figure below shows the horizontal forces acting on a car. (a) Which one of the statements describes the motion of the car? Tick one box. It will be slowing down. It will be stationary. It will have a constant speed....

Q1.The figure below shows the horizontal forces acting on a car. (a) Which one of the statements describes the motion of the car? Tick one box. It will be slowing down. It will be stationary. It will have a constant speed. It will be speeding up. (1) (b) During part of the journey the car is driven at a constant speed for five minutes. Which one of the equations links distance travelled, speed and time? Tick one box. distance travelled = speed + time distance travelled = speed × time distance travelled = speed − time distance travelled = speed ÷ time (1) Page 2 (c) During a different part of the journey the car accelerates from 9m / s to 18m / s in 6 s. Use the following equation to calculate the acceleration of the car. acceleration=.......................................................................................................................................................................................................................................................... acceleration =.................................................. m / s 2 (2) (d) Which equation links acceleration, mass and resultant force? Tick one box. resultant force = mass + acceleration resultant force = mass × acceleration resultant force = mass − acceleration resultant force = mass ÷ acceleration (1) (e) The mass of the car is 1120 kg. The mass of the driver is 80 kg. Calculate the resultant force acting on the car and driver while accelerating........................................................................................................................................................................................................................................................... Resultant force =.................................................. N (2) Page 3 (f) Calculate the distance travelled while the car is accelerating. Use the correct equation from the Physics Equation Sheet........................................................................................................................................................................................................................................................................................................................................................................................ Distance =.................................................. m (3) (g) A car driver sees a fallen tree lying across the road ahead and makes an emergency stop. The braking distance of the car depends on the speed of the car. For the same braking force, explain what happens to the braking distance if the speed doubles. You should refer to kinetic energy in your answer......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (4) (Total 14 marks) ] Page 4 Q2. 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) (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. Page 5  What can you conclude from the graph about the relationship between the load lifted and the input energy needed?................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (2) (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. Page 6 (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 7