Thermal

Question 1

Describe the process by which the volume of water in the puddle decreases [2]

Answer 1

more energetic molecules escape
from surface of liquid

Question 2

The heating element remains switched on. The temperature of the sand remains constant at a value above room temperature.
Explain why the temp remains constant [2]

Answer 2

sand is warmer than surroundings and so thermal energy constantly lost from sand
rate of thermal energy supplied to sand is equal to rate of thermal energy lost form sand

Question 3

A sealed bottle of constant volume contains air.
The air in the bottle is heated by the Sun.
What is the effect on the average speed of the air molecules in the bottle, and the average
distance between them?
A: speed dec distance dec
B speed dec distance same
C: speed inc distance inc
D: speed inc distance same

Answer 3

D

Question 4

Several ice cubes at a temperature of 0 are dropped into the water. The internal energy of the water decreases.
Give a simple molecular account of this decreaes in internal energy. [2]

Answer 4

internal energy depends on ke of molecules
ke decreases

Question 5

Explain why the volume of air in a balloon decreases when the temp decreases [2]

Answer 5

molecules less ke
pressure decreases
less collisions

Question 6

Holder has air between spaces. Explain why using holder makes it more comfortable to hold cup [3]

Answer 6

air good insulator
reduces conduction
less energy reaches hand

Question 7

Describe what happens to molecules of the liquid as its temp beings to increase [2]

Answer 7

move faster
move apart

Question 8

Describe in terms of molecules what happens when a liquid evaporates [4]

Answer 8

escape from surface of liquid
more energetic escape
less energetic left behind
temp decreases

Question 9

On a sunny day, the temp of sand on beach higher than temp of sea. Explain why [2]

Answer 9

same rate of energy supplied
shc of water much higher

Question 10

Explain why evap causes temp of remaining water to decrease [3]

Answer 10

molecules do work against attractive forces as they evap
more energetic molecules escape
average ke of molecules decreases

Question 11

Suggest why there is a delay before temp of water in glass is same as air [1]

Answer 11

glass poor conductor

Question 12

Suggest why graph steeper at solid cooling than at liquid cooling [1]

Answer 12

shc of liquid greater than shc of solid