1) A swimmer feels cold after leaving warm water on a warm, windy day.Why does she feel cold even though the air is warm? a) The less energetic water molecules on her skin escape quickly. b) The more energetic water molecules on her skin do not escape quickly. c) The water on her skin does not evaporate quickly enough to keep her warm. d) The water on her skin evaporates quickly and cools her skin. 2) The gas in a container is heated but is kept at constant volume.Why does the gas pressure increase? a) The molecules expand. b) The molecules increase in mass. c) The molecules move further apart. d) The molecules move more rapidly. 3) The molecules of a substance become more closely packed and move more quickly.What is happening to the substance? a) A gas is being heated and compressed. b) A gas is being heated and is expanding. c) A liquid is boiling. d) A liquid is evaporating at room temperature. 4) The diagram shows four labelled changes of state between solid, liquid and gas.Which changes need an energy input? a) P and Q b) Q and R. c) R and S d) S and P 5) A cotton sheet is ironed with a hot electric iron.How is energy transferred through the metal base of the iron to the sheet? a) by conduction only b) by convection only c) by radiation only d) by convection and radiation only 6) The diagram shows a vacuum flask used to keep liquid hot.How does thermal energy pass through the vacuum? a) conduction only b) convection only c) radiation d) conduction and convection 7) The diagram shows a block of ice placed in a warm room.At which point is the temperature the lowest? a) A b) B c) C d) D 8) The air in a room is heated by a heater. The diagram shows the circulation of the air in the room.Which statement about the air that is heated is correct? a) The air contracts and becomes less dense. b) The air contracts and becomes more dense. c) The air expands and becomes less dense. d) The air expands and becomes more dense 9) A girl is outdoors. She warms her hands by holding them near a fire, as shown.How does the heat from the fire reach her hands? a) conduction only b) convection and conduction c) convection and radiation d) radiation only 10) Ice is trapped by a metal gauze at the bottom of a tube containing water.The water is heated strongly at the top, but the ice only melts very slowly. Why its melts very slowly. a) Heat energy always travels upwards. b) Hot water is more dense than cold water. c) Metal gauze does not allow heat to pass through. d) Water is a poor conductor of heat.

THERMAL PHYSICS

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