Grade 10 Science

The three plate boundaries are: (1) Divergent - plates move apart, creating mid-ocean ridges and rift valleys (seafloor spreading). (2) Convergent - plates collide, forming mountains, trenches, and volcanic arcs. Subduction occurs when oceanic plate goes under continental plate. (3) Transform - plates slide past each other horizontally, causing earthquakes along fault lines (e.g., San Andreas Fault).

The electromagnetic spectrum arranges EM waves by frequency/wavelength. From lowest to highest frequency: Radio waves (communication), Microwaves (cooking, radar), Infrared (heat, night vision), Visible light (human vision), Ultraviolet (sterilization, skin effects), X-rays (medical imaging), Gamma rays (cancer treatment, sterilization). All EM waves travel at the speed of light (3×10⁸ m/s) in vacuum.

Newton's Laws: (1) Law of Inertia - objects at rest stay at rest, objects in motion stay in motion unless acted upon by external force. (2) F = ma - acceleration is directly proportional to net force and inversely proportional to mass. (3) Action-Reaction - for every action, there's an equal and opposite reaction. These laws explain all motion from walking to rocket propulsion.

Natural selection works through: (1) Variation - individuals have different traits, (2) Inheritance - traits are passed to offspring, (3) Selection pressure - environment favors certain traits, (4) Survival & reproduction - organisms with favorable traits survive and reproduce more. Over generations, beneficial traits become more common, leading to evolution and potentially new species (speciation).

Biodiversity refers to the variety of life at three levels: (1) Species diversity - number of different species, (2) Genetic diversity - variation within species, (3) Ecosystem diversity - variety of habitats. Importance: maintains ecosystem stability, provides food/medicine sources, enables pollination and nutrient cycling, and supports economic resources. Loss of biodiversity threatens ecosystem collapse.

Energy flows in one direction through trophic levels: Producers (plants) → Primary consumers (herbivores) → Secondary consumers (carnivores) → Tertiary consumers (top predators) → Decomposers. Only about 10% of energy transfers to the next level (10% rule). Energy is lost as heat at each level. This explains why there are fewer top predators than herbivores.

Kinetic energy (KE) is energy of motion: KE = ½mv². It depends on mass and velocity. Potential energy (PE) is stored energy due to position or condition. Gravitational PE = mgh (mass × gravity × height). The Law of Conservation of Energy states that total energy remains constant - it can transform between forms but cannot be created or destroyed.

Both are caused by plate tectonics. Earthquakes occur when stress builds up at plate boundaries and releases suddenly, sending seismic waves. The focus is the underground origin; the epicenter is directly above on surface. Volcanic eruptions occur when magma rises through the crust, typically at convergent boundaries (subduction) or divergent boundaries (rift zones). The Pacific Ring of Fire has most activity.