Physics Chapter on Density and Fluid Dynamics

Density & Mass

• A cube of ice measuring 2 cm on each side has a density of 0.92 g/cm³. The mass of the ice cube is 7.36 g.
• A metal block has a volume of 500 cm³ and a mass of 8 kg The density of the metal is 16 g/cm³.
• A liquid with a specific gravity of 0.8 has a density of 0.80 g/cm³.

Fluid Dynamics

• Water flowing through a horizontal tube with an unequal area of cross-section, at the most narrow place: velocity of water is maximum and pressure minimum.
• A hydraulic lift with a small piston of 2 cm diameter and a large piston of 10 cm diameter, a force of 100 N applied to the small piston results in 2500 N exerted by the large piston.
• Gases are compressible fluids.
• A tank containing water 1 meter high with a leak hole 20 cm from the bottom. The speed of water coming out of the hole is 4.00 m/s.
• Pressure increases with the increase in the weight of an object.

Archimedes' Principle & Buoyancy

• Archimedes' principle states: Buoyant force is the weight of the volume of water displaced by an immersed object.
• An iceberg is submerged to 91.7% below the water if the density of ice is 917 kg/m^3 and the density of water is 100 kg/m^3.

Pressure

• A scuba diver at a depth of 20 meters experiences an increase in pressure due to water of 2 atm.
• In a U-shaped tube containing water and oil (specific gravity 0.8), if the water column height is 10 cm, the oil column height is 12.5 cm.
• Atmospheric pressure is measured using a barometer.

Pascal's Principle & Bernoulli’s Principle

• Pascal's principle states: When an external pressure is applied to a fluid, the pressure in the fluid increases equally throughout.
• A boat floats in water because the boat is less dense than the water it displaces.
• Bernoulli's principle states: As the velocity of a fluid increases, its pressure decreases.

Fluid Flow

• Laminar flow is characterized by smooth, straight, and steady flow.
• Torricelli's Theorem states: The speed of a fluid flowing out of an opening in a container is equal to the square root of twice the product of the acceleration due to gravity and the height of the fluid above the opening.

Wave Properties

• An elastic spring stretched and released produces a longitudinal wave.
• The amplitude of a sound wave determines its loudness.
• Energy transmission by waves examples: light shining on a surface, heat transfer by convection, and sound vibrating through a medium.

Light & Optics

• The bending of light as it passes from one medium to another of different optical density is called refraction.
• Polarized light oscillates in a single plane.
• The splitting of white light into its component colors is called dispersion.
• A concave lens is used to correct nearsightedness.
• The wavelength and frequency of light are inversely proportional.
• For a telescope, the larger the diameter of the objective lens, the greater the resolving power.
• Destructive interference occurs when two waves of equal amplitude and frequency cancel each other out.
• The Doppler effect describes the change in the frequency of a wave as the source or the observer moves.
• The inverse square law states: Illumination decreases as the square of the distance increases.

Lenses & Images

• A convex lens is thicker at the center than at the edges.
• An object of height 5 cm placed 25 cm in front of a bi-convex lens with a focal length of 10 cm produces an image 3.4 cm high.

Color

• A purple cabbage is colored purple because it reflects only purple light.

Radiation

• Radiation exposure can have both Stochastic and Deterministic effects
• Stochastic effects of radiation exposure occur randomly and have a probability of occurrence. Examples include cancer and genetic mutations.
• Deterministic effects are predictable and occur after a certain threshold dose. Examples include cataracts and skin burns.
• Sensitive organs to radiation include bone marrow, liver, lungs, and kidneys.
• RBE (Relative Biologic Effectiveness) measures the damage a particular type of radiation does to living tissue compared to X-rays.
• There is no safe radiation dose.
• Radiation protection principles include Time, Distance, and Shielding.

Atoms

• An atom with an atomic number of 14 and a mass number of 28 has 14 neutrons (mass number - atomic number = number of neutrons).

Radioactive Decay

• A radioactive material with a half-life of 10 days means that half of the material will decay in 10 days.