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28. The diagram shows a distance-time graph for a vehicle.
Which row describes the motion of the vehicle in region P and in region Q of the graph?
29. A metal block is heated until it is completely melted. None of the melted metal evaporates.
The metal now solidifies.
What happens to the mass of the metal during the changes of state?
30. The diagram shows a solid rectangular block made of material of density 2.0 g / cm3.
What is the mass of the block?
31. A worker carries bricks up a ladder.
The following quantities are known.
● the height the bricks are lifted up
● the time taken for the worker to lift the bricks
● the volume of the bricks
● the weight of the bricks
Which quantities are needed to calculate the useful power produced by the worker as he carries
the bricks up the ladder?
height, time and volume
height, time and weight
height, volume and weight
time, volume and weight
32. A gas is contained in a cylinder of constant volume.
The gas is cooled and this causes its pressure to change.
What happens to the speed of the molecules of the gas, and what happens to the pressure of the
33. A boy sits near a campfire. He holds an iron bar with one end in the fire. His hand becomes hot.
In which ways does thermal energy (heat) from the fire reach his hand?
conduction and convection only
conduction and radiation only
convection and radiation only
conduction, convection and radiation
34. The diagram represents a wave.
How many wavelengths are there between X and Y?
35. A plane mirror is used to form an image of an object.
At which labelled point is the image formed?
36. Which group of electromagnetic radiations is arranged in order of increasing frequency?
infra-red, visible light, ultraviolet
ultra-violet, visible light, radio waves
X-rays, radio waves, γ-rays
γ-rays, X-rays, infra-red
37. Four loudspeakers each vibrate at the frequencies shown.
Which loudspeaker produces the highest-pitched sound that can be heard by a human?
5.0 × 103 Hz
15 × 103 Hz
25 × 103 Hz
35 × 103 Hz
38. Which row gives the unit for energy and the unit for electromotive force (e.m.f.)?
39. Three charged balls P, Q and R are suspended by insulating threads. Ball P is negatively
What are the signs of the charges on ball Q and ball R?
40. The diagrams represent pairs of nuclei of some atoms.
Which pair shows nuclei of different isotopes of the same element?