1.
The diagram in Box A shows a vase with a heavy base. Its centre of mass is indicated with a black dot.
Box ABox B
a. The vase is tilted at an angle so that it is just about to topple. In box B draw a diagram of the tilted vase showing clearly the location of the centre of mass. (1 mark)
b. State what happens to the position of the centre of mass when the vase is full of water.
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c. State and explain how this affects the stability of the vase.
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2.
Some scientists believe that, in an atom, electrons move at a steady speed in circular orbits around the nucleus.
a. Explain why a force is needed to keep the electron orbiting even though it is at a steady speed.
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b. What real force provides the necessary force in this situation?
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c. How would the speed of outer-shell electrons compare to the speed of inner-shell electrons?
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d. Other scientists suggest that an electron in this orbit would radiate energy and so gradually slow down. How do scientists resolve disagreements like this?
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3.
The diagram shows a convex lens and an object (arrow).
a. Complete the diagram to find the image using construction rays.
FF
(2 marks)
b. Describe the nature of the image.
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c. Suggest a use for the lens in this arrangement.
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4.
A ship’s depth finder shows the distance below a ship to the sea-bed. The depth finder sends pulses of ultrasound to the sea-bed and times the reflection to work out the depth.
a. Calculate the depth of the sea if the pulse takes 20ms to return to the ship. (The speed of ultrasound in water is 1100m/s. 1000ms = 1s)
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The depth finder can also obtain information from the reflected ultrasound pulse about the type of rock making up the sea-bed.
b. How will different types of rock affect the reflected ultrasound pulse?
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5.
Iron objects that are left in the ground for a long time become slightly magnetised by the Earth’s field.
a. A metal detector consists of a coil of 5 turns of wire attached to a voltmeter. Explain why, as the coil is passed over a hidden piece of magnetised iron, the meter reading changes.
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The graph shoes how the meter reading changes as the detector coil is moved across the top of the iron.
Voltmeter reading / mV
Time / ms
b. Explain why the meter reading changes in this way.
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c. The metal detector is not very sensitive. Explain what the word sensitive means.
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d. How could you improve the sensitivity of the metal detector?
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6.
a. What is the milky way? (Amusing answers receive no credit.)
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b. The Sun is in a stable phase of its lifecycle. Explain how the forces on the Sun keep it stable for a long period.
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c. When the Sun runs out of fuel it will become a red giant and then a white dwarf star before finally dying. Explain how the lifecycle of a much heavier star would differ from that of the Sun.
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7.
John is investigating refraction of light by a prism.
a. Complete the diagram to show the path taken by the ray of green light through and beyond the prism.
Ray of green light
(2 marks)
b. Describe and explain the change in direction as the light enters the glass.
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John measures the angle of the outgoing ray for different wavelengths of incident light.
Wavelength / nm / Outgoing angle / degreesTrial 1 / Trial 2 / Trial 3 / Average
500 / 42 / 43 / 35 / 40
510 / 37 / 35 / 36 / 36
520 / 33 / 33 / 33 / 33
530 / 31 / 30 / 32 / 31
540 / 29 / 29 / 32 / 30
550 / 27 / 28 / 29 / 28
c. The measurements for which wavelength show the least precision?
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Explain how you know.
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d. John now uses his results to find the wavelength of some green light. What is the name for this process whereby a measuring device is first set-up using known values so that it can then be used on unknown values?
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END OF QUESTIONS