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حل مراجعة الوحدة الخامسة States of Matter منهج انسباير Inspire

Topic 5: States of Matter – Summary (Laws & Formulas Excluded)

Pressure Basics

· Pressure is the force applied per unit area.
· Units of pressure include Pascals and Newtons per square meter.
· Pressure depends on force and the area over which it is applied.
· Smaller area = greater pressure for the same force.

Atmospheric Pressure & Temperature

· Atmospheric pressure at sea level is about 100 kPa.
· Absolute zero is the lowest possible temperature, at which particles have minimum motion.
· Temperature in gas behavior is measured in Kelvin.

Behavior of Gases

· When a gas is heated at constant pressure, its volume increases.
· Gas volume is directly related to its Kelvin temperature at constant pressure.
· Gas pressure and temperature are directly related when volume is constant.

Pressure in Liquids

· Pressure in a liquid depends on depth, liquid density, and gravity.
· It does not depend on the shape of the container or the volume of liquid.
· At the same depth, pressure is the same in all directions and in all containers.

Buoyancy & Archimedes&039; Principle

· Buoyant force acts upward on objects in fluids.
· An object floats if it is less dense than the fluid.
· An object sinks if it is more dense than the fluid.
· Neutral buoyancy occurs when object density equals fluid density.
· Buoyant force depends on the volume of fluid displaced and fluid density, not on the object&039;s depth or weight.
· A floating object displaces a volume of fluid equal to its own weight.
· A fully submerged object displaces a volume equal to its own volume.

Floating, Sinking, and Apparent Weight

· Apparent weight of an object in fluid is less than its actual weight due to buoyancy.
· An object floats if buoyant force is greater than or equal to its weight.
· An object sinks if buoyant force is less than its weight.
· Tension in a string or scale reading decreases when an object is submerged.

Real-World Applications

· Ships float because their shape allows them to displace a large volume of water, even though they are made of dense materials.
· Ice floats because it is less dense than liquid water.
· Submarines control buoyancy by taking in or expelling water to change their average density.
· Fish adjust their swim bladder volume to control depth.
· Hot air balloons rise because hot air inside is less dense than the cooler air outside, creating an upward buoyant force.

Key Comparisons

· Equal volumes of different materials experience the same buoyant force if fully submerged in the same fluid.
· A partially submerged object experiences less buoyant force than when fully submerged.
· Buoyant force on a floating object equals the object&039;s weight.
· Buoyant force on a sinking object is less than its weight.