Why do solids have definite shape and volume?
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Their molecules are very close to each other
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Their molecules have strong forces of attraction and
repulsion
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Their molecules vibrate about fixed positions
Why do not liquids have fixed shape but have definite volume can flow?
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Their molecules are further apart from each other.
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Their molecules have weaker forces of attraction and
repulsion
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Their molecules vibrate but can change position with
other molecule
Why do not gases have fixed shape, and definite volume but can flow?
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Their molecules are much further apart from each other.
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Their molecules have negligible forces between them.
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Their molecules move randomly in all directions
Explain why gases are easily compressed?
Gases are easily compressed because their repulsive
intermolecular forces are negligible.
Why liquids are used to transfer forces in hydraulic machines?
Because they are much harder to compress than gases.
Explain why a spring returns to its original shape after
removing the stretching force?.
When the spring is extended by a load, the intermolecular spaces
are increased and the attractive forces between the molecules cause it to
return to its original length when the load is removed.
Explain why a spring returns to its original shape after releasing
compression from it?
When the spring is compressed by a force, the intermolecular
spaces are decreased and the repulsive forces between the molecules cause it
to return to its original length when the force is removed.
Define temperature based on the
molecular model?
Temperature is a measure of the average kinetic energy possessed
by each molecule of the substance
What is the relation between temperature and kinetic energy
of molecules?
The hotter the object, the more kinetic energy its molecules have
and the faster they move.
What does it mean when an object is
hotter than another object based on the molecular model?
It means the average kinetic energy
of each molecule of the hot object is greater than the average
kinetic energy of the colder one.
Explain how gases produce pressure on the walls
of their containers?
Gas molecules are in a state of continuous motion in all
directions, and they are constantly bombarding the walls of the
container. When the molecules bounce off the walls, they produce an outward
force on the walls which causes the outward pressure of the gas on
the walls of the container.
Explain how temperature increase the pressure of gases?
When the temperature rises, the gas molecules gain kinetic energy
and move faster and thus strike the container wall more frequently and with
greater force. Therefore, the total force exerted per unit area of the
walls is greater and the pressure increase.
Explain how low temperature
decrease the pressure of gases?
When the temperature decreases, the gas molecules lose kinetic
energy and move slower and thus strike the container wall less frequently
and with less force. Therefore, the total force exerted per unit area
of the walls is less and the pressure decreases.
What is meant by a Brownian motion? Brownian motion is a random motion.
Explain an experiment to demonstrate the Brownian motion.
