Level 7 Physics Questions 1. Three pupils took part in an investigation into the speed of sound. All three pupils stood 1020 m from an explosion. Sylvia wore a blindfold. Paul wore ear defenders. James wore a blindfold and ear defenders. He rested his head on a wooden stick pushed into the ground so that he could feel vibrations. The explosion produced sound and light at the same time. The table shows the speed of sound in two different materials. material Speed of sound (m/s) air 340 soil 3200 (a) Use all the information above to help you answer parts and below. In which order would the pupils notice the explosion? first... second... third... From the information given, calculate the time it would take for the sound to travel through the air to Sylvia.... s (b) Another pupil, Nasah, stood 2000 m away from the explosion. Moulsham High School 1
The sound heard by Nasah was quieter than the sound heard by Sylvia. The further sound travels the quieter it becomes. Give the reason for this. The oscilloscope trace below represents the sound Sylvia heard. The sound Nasah heard was quieter but the pitch was the same. On the right-hand grid, draw the trace to show the pattern of the sound Nasah heard. maximum 5 marks 2. A father makes a simple mobile for his young son. He uses plastic animals as shown below. Moulsham High School 2
(a) The elephant weighs 0.2 N. What is the turning moment produced by the elephant about point X? Give the unit. What is the turning moment produced by the monkey about point X? (iii) What is the weight of the monkey?... N (b) What is the size of the tension (force) in string A?... N maximum 5 marks 3. A reed switch is made of two iron strips inside a glass tube. The iron strips close together when a magnet is brought near. They spring apart again when the magnet is removed. Moulsham High School 3
(a) Hilary set up the circuit shown below. She tried to close the reed switch using an electromagnet. She closed switch E but the electromagnet was not strong enough to close the reed switch. Give two ways Hilary could increase the strength of the electromagnet. 1.... 2.... Hilary increased the strength of the electromagnet. The reed switch closed. The iron strips were magnetised as shown below. She reversed the current in the coil of the electromagnet. On the diagram below, label the poles of the iron strips when the current was reversed. (b) Iron and steel are both magnetic materials. Explain why the strips must be made of iron and not steel. Moulsham High School 4
She replaced the reed switch with a piece of copper wire. The current through the bulb increased. Explain why more current flowed through the bulb when the reed switch was replaced with copper wire. maximum 5 marks 4. John used an electrical heater to heat a cup of water. He kept stirring the water. When the temperature reached 20 C, he started his stopwa tch and measured the temperature of the water every half minute. Moulsham High School 5
He switched off the heater after 4 minutes, but continued to record the temperature. His results are shown in the table. One measurement is missing and another appears to be wrong. Time (minutes) Temperature (ºC) 0.0 20 0.5 26 1.0 31 1.5 36 2.0 41 2.5 46 3.0 3.5 57 4.0 56 4.5 58 5.0 59 5.5 59 (a) Use the results in the table to draw a graph on the grid. Label the axes. Plot the points and draw a smooth curve of best fit. ( ) ( ) Moulsham High School 6
4 marks Moulsham High School 7
(b) From your curve, estimate the temperature of the water after three minutes.... C maximum 5 marks 5. (a) The diagram below shows a car park barrier. 0.1m pivot 1.5m barrier iron counterweight 50 N Calculate the turning moment produced by the barrier about the pivot. Give the unit. The barrier is horizontal. The weight of the barrier is balanced by an iron counterweight. Calculate the downward force produced by the counterweight.... N Moulsham High School 8
(b) An electromagnet is placed beneath the iron counterweight as shown below. iron counterweight battery electromagnet iron core When the switch is closed the barrier rises. Explain how the electromagnet can be used to raise the barrier................ maximum 5 marks 6. (a) Megan was doing time-trials on her bike around a 400 metre horizontal track. She took 32 seconds to travel 400 m. What was her average speed? Give the unit. Compare the forward force on the bike with the backward force on the bike when Megan was travelling at a constant speed. Moulsham High School 9
(b) Megan then crouched down over the handlebars to make herself more streamlined, as shown below. She continued to pedal with the same force as before. Compare the forward and backward forces on Megan and her bike now....... Explain your answer....... maximum 4 marks 7. The drawing below shows a solar panel fixed to the roof of a house in Britain. Moulsham High School 10
(a) Daniel measured the energy output from this solar panel during one day in June. The graph below shows his results. 1.2 1.0 energy output (kj/s) 0.8 0.6 0.4 0.2 0 2am 4am 6am 8am 10am noon 2pm 4pm 6pm 8pm 10pm 12pm time of day Why does the energy output from the solar panel vary during the day? Daniel used the solar panel to run a motor. The motor needs 0.7 kj/s to run at full speed. Use the graph to find out how long Daniel s motor would run at full speed.... hours Moulsham High School 11
(b) Daniel measured the energy output from a different solar panel. This type of solar panel turns so that it always faces the Sun. The graph below shows the energy output for this panel during one day in midsummer. 1.2 1.0 energy output (kj/s) 0.8 0.6 0.4 0.2 0 2am 4am 6am 8am 10am noon 2pm 4pm 6pm 8pm 10pm 12pm time of day On the graph above draw another curve to show how the energy output for this solar panel might vary on a day in mid-winter. Between 7am and 7pm the solar panel turns through an angle of 180. Calculate the angle the solar panel turns through each hour....degrees maximum 5 marks Moulsham High School 12
8. A remote-controlled car was timed over a period of 10 seconds. A graph of distance against time is shown below. 20 16 distance, in metres 12 8 4 0 0 2 4 6 8 10 time, in seconds (a) Describe the motion of the car between: 2 seconds and 6 seconds; 9 seconds and 10 seconds. (b) Calculate the average speed of the car between 0 and 10 seconds. Give the unit....... Moulsham High School 13
(c) The diagram below shows two of the forces acting on the car when it is moving. When the motor was switched off, the car slowed down and then stopped. While the car was slowing down, which of the following was true? Tick the correct box. Friction was zero and the forward force was greater than zero. The forward force was zero and friction was greater than zero. Friction was zero and the forward force was zero. The forward force and friction were both greater than zero. Use the graph to find the time when the car started to slow down. The car started to slow down after... s. Maximum 6 marks Moulsham High School 14
9. Alex has a 100 cm ruler pivoted at the centre. She ties a balloon filled with carbon dioxide 16 cm from the pivot, as shown below. The total weight of the balloon and carbon dioxide is 0.06 N. metre ruler 16 cm 0 10 20 30 40 50 60 70 80 90 100 pivot balloon filled with carbon dioxide gas 0.06 N (a) The ruler becomes unbalanced. Calculate the turning moment the balloon produces about the pivot on the ruler. Give the unit....... Moulsham High School 15
(b) Alex ties another similar balloon, filled with helium, 48 cm from the pivot. The helium balloon exerts an upward force on the ruler. The ruler is balanced as shown below. balloon filled with helium gas 48 cm metre ruler 16 cm 0 10 20 30 40 50 60 70 80 90 100 pivot balloon filled with carbon dioxide gas 0.06 N When the ruler is balanced, what turning moment must the helium balloon produce about the pivot? Calculate the upward force exerted by the helium balloon on the ruler.... N Maximum 4 marks Moulsham High School 16
10. Sunita puts on a pair of special glasses as shown below. The glasses have coloured filters in them. (a) Sunita looks at a lamp through the green filter. The lamp gives out white light, but appears to be green. Explain how this is possible.......... (b) Sunita looks at a red lamp. What colour will the lamp appear to Sunita, if she looks at it through the red filter? Explain your answer. What colour will the lamp appear to Sunita, if she looks at it through the green filter? Explain your answer. Maximum 5 marks Moulsham High School 17