NCEA LEVEL 1 PHYSICS

Heat Quiz

Question One

One way of preventing hypothermia is by using emergency blankets when a tramper gets cold.  Emergency blankets are thin sheets with one side made of shiny silver coloured foil. The emergency blanket is wrapped around the tramper with the shiny side facing inside, towards their body.  Explain why a person will be warmer with the silver side of the blanket facing towards your body rather than facing outwards.

Question Two

A good way of keeping warm and preventing hypothermia is to drink hot sweet drinks. A gas stove is used to boil hot water in a metal pot to make hot chocolate.   Name the process by which heat energy is transferred through the bottom of the pot to the water. 

Question Three

Name the process by which heat is then spread throughout the water. 

Question Four

Discuss how this process spreads the heat throughout the water.

Question Five

Explain why the base of the pot is made of metal, but the handle is covered in plastic.

Question Six

A fridge keeps food and drink cold, even on a very hot day. A fridge cools its contents by pumping cool liquid (called coolant) through pipes in the top of the fridge.  In a fridge the coolant flows through pipes in the ice box, cooling the air around the ice box. The icebox is in the centre top of the fridge. The rest of the air in the fridge is cooled by convection currents.  Discuss how convection currents cool all the air in the fridge.

Question Seven

Discuss how the design of a fridge (white outer casing, thick walls lined with polystyrene, rubber seals around the door) prevents the transfer of heat from the surrounding areas into the fridge.

Question Eight

Fiona parks her car is in full sunshine. When she returns to the car she finds that it is quite hot inside. To cool it down she winds the windows down a little.
She decides that heat has entered through the glass of the closed windows. State the type of heat transfer that happens through clear glass.

Question Nine

Discuss how the colour of a car and slightly open windows could affect the temperature inside the car.

Question Ten

It is the start of the Winter Sports season and Ruth has been working out at the gym. After her workout she goes to the changing room, which is at 25 °C and well ventilated. While sitting on a bench recovering, she loses heat to the surroundings in several ways,
Complete the table below by filling in the blank spaces.

Question Eleven

Suddenly the door to the changing room is opened by another sportswoman.  Which type of heat transfer would increase the most? Discuss your reasoning.

Question Twelve

A student also is using a gas heater to keep the room warm.  Use the following diagram of her study to answer the questions that follow.

She notices that when she studies late at night with the heater on, that her feet get cold yet when she stands up, the air feels quite warm.

Which method of heat transfer best describes the warmth from the heater rising to the top of the room? 

Question Thirteen

Explain how insulation in the ceiling helps to keep the room warm.

Question Fourteen

After leaving the chair next to the heater for a long time, the student notices that it also feels warm.  Discuss the effect of the colour and texture of the chair on the amount of radiant energy it absorbs when sitting close to the heater.

Question Fifteen

Explain why it is important that she should keep the curtains shut when trying to keep the room warm.

Question Sixteen

After turning the heater off the room remained warm for another hour.  Use scientific ideas to discuss three methods that may be used to keep your house warm.