- A. begin to move faster
- B. lose energy
- C. become heavier
- D. become lighter
(a) begin to move faster
- A. newton
- B. joule
- C. volt
- D. Celsius
(b) joule
- A. 80°C
- B. More than 50°C but less than 80°C
- C. 20°C
- D. around 40°C
(d) around 40° C
- A. flow from iron ball to water.
- B. not flow from iron ball to water or from water to iron ball.
- C. flow from water to iron ball.
- D. increase the temperature of both.
(b) not flow from iron ball to water or from water to iron ball.
hot, cold
temperature
Kelvin
expand, contract
equilibrium
True
False – Steam is formed when the heat is absorbed from the water.
False – Thermal expansion is always not a nuisance.
True
False – Unit of heat and temperature are different.
The reason is that the borosilicate glass does not expand much on being heated and therefore they do not crack.
During summer thermal expansion takes place in electric wire.
In winter it contracts so it becomes straight.
When we heat rivet expansion takes place and becomes soft.
One end of the rivet is hammered to form a new head.
When cooled, the rivet will contract and hold tightly.
Kelvin
100° C
Temperature
Water heater, Iron box, Electric kettle, Micro oven.
The expansion of a substance on heating is called thermal expansion.
When two objects in thermal contact, no longer affect each other’s temperature, there exists Thermal equilibrium.
When we heat solids the vibrations and movement of molecules will increase.
The temperature of the object increases.
The distance between molecules will increase.
Thermal expansion: The expansion of a substance on heating is called, the thermal expansion of that substance.
Fitting the iron rim on the wooden wheel:
The diameter of the iron ring is slightly less than that of the wooden wheel.
So, it cannot be easily slipped on from the rim of a wooden wheel.
The iron ring is, therefore, first heated to a higher temperature so that it expands in size and the hot ring is then easily slipped over to the rim of the wooden wheel.
Coldwater is now poured on the iron ring so that it contracts in size and holds the wooden wheel tightly.
Rivetting:
Rivets are used to join two steel plates together.
Hot rivet is driven through the hole in the plates.
One end of the rivet is hammered to form a new rivet head.
When cooled, the rivet will contract and hold the two plates tightly together.
Cracking of a thick glass tumbler:
Glass is a poor conductor of heat.
When hot liquid is poured into the tumbler, the inner surface of the tumbler becomes hot and expands while the outer surface remains at room temperature and does not expand.
Due to this unequal expansion, the tumbler cracks.
When a window is left open on a winter night I will feel uncomfortable because the heat is escaping from the room.
The heat will transfer from high temperature to low temperature.
During winter cold air enters the room, so room temperature will decrease.
When our body temperature is lower than normal temperature, We feel hot from the surrounding.
Because the surrounding temperature will be high compare to our body.
Many of us “expect” that the diameter of the hole will decrease because the circular disk is free to expand in all directions as well. Note that expansion of metal due to heating is not like gas spreading out wherever space is available. The correct way to think about it is as follows: Hole size is irrelevant in this case. So we can think that hole is very large.
If we carve a hole so large that its radius is slightly less than that of the circular disk itself, then we will have a ring. It is obvious that the radius of the ring will increase, as atoms have more energy so their oscillation amplitude will increase. As the diameter of the ring increases, the diameter of the hole will also increase.
For example, if you want to insert one hallow pipe inside another hollow pipe of the same diameter, just heat anyone and insert the second one into the heated pipe. This explains the answer in an easy way. So it says that diameter will increase with increasing temperature.
- A. Electric
- B. Heat
- C. Chemical
- D. Kinetic energy
(b) Heat
- A. America
- B. Africa
- C. Antarctica
- D. Europe
(b) Africa
- A. 0° C
- B. 32° C
- C. 100° C
- D. 110° C
(c) 100°C
- A. heat energy
- B. kinetic energy
- C. potential energy
- D. light energy
(a) heat energy
Reason: During summer thermal expansion takes place.
The main source of heat is Sun.
Other sources are combustion, friction and electricity.
Heat is an energy that raises the temperature of a thing by causing the molecules in that thing to move faster.
Two objects in thermal contact have same temperature they are said to be in thermal equilibrium.