VOCAB
What is the temperature at which a solid becomes a liquid?
Melting point.
What is the most common state of matter in the universe?
Plasma.
Which state of matter has a definite shape and a definite volume?
A solid.
Write the formula for pressure in terms of force and area.
P = F ÷ A.
Which principle states that pressure applied to a confined fluid is transmitted equally in all directions?
Pascal’s principle.
What term describes a fluid’s resistance to flowing?
Viscosity.
At what point does a liquid’s vapor pressure equal the external pressure acting on its surface?
The boiling point.
According to Boyle’s law, what happens to gas volume when pressure increases at constant temperature?
Volume decreases; pressure and volume are inversely related.
A force of 600 N acts on an area of 3.0 m². What pressure is applied?
P = F/A = 600 N ÷ 3.0 m² = 200 Pa.
Which principle states that a fluid’s pressure decreases as its speed increases?
Bernoulli’s principle.
What is the ability of a fluid to exert an upward force on an object immersed in it?
Buoyancy.
Why can a steel boat float even though a solid steel block sinks?
The boat’s shape lets it displace enough water for the buoyant force to balance its weight; the block does not displace enough water relative to its weight.
How are temperature and the average kinetic energy of particles related?
Temperature represents the average kinetic energy of particles; higher temperature means greater average kinetic energy.
A gas has a volume of 10.0 L at 100 kPa. If pressure increases to 200 kPa at constant temperature, what is the new volume?
Boyle’s law: P₁V₁ = P₂V₂. V₂ = (100 kPa × 10.0 L) ÷ 200 kPa = 5.0 L.
A student heats ice until it becomes steam. What is happening to the particles during melting and boiling plateaus on a heating curve?
Added energy is used to overcome attractions between particles and change state; temperature remains constant during each plateau
What is the amount of energy required to change a liquid at its boiling point into a gas?
Heat of vaporization.
Using Bernoulli’s principle, explain why strong winds can lift a roof during a tornado.
Fast-moving air over the roof has lower pressure; the relatively higher pressure inside the building can push the roof upward.
Compare the particle behavior during a sloped section and a flat plateau on a heating curve.
On a slope, particles gain kinetic energy and temperature rises. On a plateau, added energy changes potential energy and overcomes attractions between particles, so temperature stays constant during the state change.
A 1.5-L balloon is at 25.0°C. What is its volume at 90.0°C if pressure stays constant? Use K = °C + 273.
T₁ = 298 K; T₂ = 363 K. Charles’s law: V₁/T₁ = V₂/T₂. V₂ = 1.5 L × 363 K ÷ 298 K ≈ 1.83 L.
Water pressure is 1,100 kPa and pushes on a fish with an area of 0.50 m². What force does the water exert? Use F = PA.
Convert 1,100 kPa to 1,100,000 Pa. F = PA = 1,100,000 Pa × 0.50 m² = 550,000 N.
What process changes a solid directly into a gas without becoming a liquid first?
Sublimation.
A helium balloon rises through the atmosphere. Describe how the decreasing outside pressure affects the gas inside and the balloon’s volume.
As atmospheric pressure decreases, the gas expands and the balloon’s volume increases; it may eventually burst if it expands beyond its limit.
A balloon contains air and falls to the floor, but a helium balloon rises. Explain using density and buoyant force.
An air-filled balloon is denser than the surrounding air overall, so its weight exceeds the buoyant force and it falls. A helium balloon is less dense than surrounding air, so the buoyant force exceeds its weight and it rises.
A gas has a volume of 25 L at 200 kPa and 25°C. Find its volume at 250 kPa and 0°C. Use K = °C + 273.
Combined gas relationship: P₁V₁/T₁ = P₂V₂/T₂. T₁ = 298 K; T₂ = 273 K. V₂ = (P₁V₁T₂)/(P₂T₁) = (200 × 25 × 273)/(250 × 298) ≈ 18.3 L.
A hydraulic lift has a large piston area of 3.0 m² with a downward force of 1,500 N. What force on a small piston of area 0.08 m² would balance the pressure? Show the relationship.
Pascal’s principle: F₁/A₁ = F₂/A₂. Large-piston pressure = 1,500 N ÷ 3.0 m² = 500 Pa. Small-piston force = 500 Pa × 0.08 m² = 40 N.