Chapter 11 Force & Motion: Science Final Exam

Chapter 11: Force & Motion

• Motion is a change in position over time, measured by distance (m) and speed (m/s)
• Distance-time graph represents motion, with steeper lines indicating faster speeds
• Initial distance and end distance are measured, with uniform motion showing a straight line
• Non-uniform motion shows a curved line, with acceleration and deceleration

Force & Motion

• Force (N) causes a change in speed or direction
• Forces can be contact (push, pull, friction, air resistance) or non-contact (gravity, magnetic, electrostatic)
• Unbalanced forces result in motion, while balanced forces result in no motion
• Spring balance measures force, and free-body diagrams show forces acting on an object

Gravity

• Gravity is a force that pulls objects towards each other, with the Earth's gravity pulling objects towards its center
• Gravity affects objects with mass, regardless of their size or shape
• Weight is the force of gravity acting on an object, with mass remaining constant regardless of location
• Friction opposes motion, and air resistance slows down objects moving through the air

Friction

• Friction occurs when two surfaces come into contact, opposing motion
• Ways to reduce friction include using rollers, ball bearings, air cushions, and lubricants
• Material surfaces, such as rubber or glass, can also reduce friction

Action & Reaction

• Action and reaction forces are equal and opposite, with one object exerting a force on another object
• Action and reaction forces are of the same type, with contact and non-contact forces possible
• Drawing action and reaction forces can help illustrate the concept

Chapter 10: Sensing the Environment

• Sense organs, such as eyes, contain sensory cells or receptors that respond to stimuli

• Stimuli trigger signals that are transmitted to the brain

• The eye is a sense organ that responds to light, with the following structures:

  • Cornea: allows light to enter
  • Sclera: protects the eyeball's shape
  • Retina: contains light receptors
  • Optic nerve: carries signals from light receptors to the brain
  • Lens: focuses light
  • Blind spot: area where light receptors are absent, but no signal is sent### Eye Structure and Function

• The eye has a lens that changes thickness to focus on near or far objects, and a pupil that controls the amount of light entering the eye.

• The lens contracts to thicken for near vision and relaxes to thin for far vision.

• The pupil is small in bright light to protect the eye from damage and large in dim light to allow more light to enter.

Light Receptor Cells

• There are two types of light receptor cells: cones and rods.
• Cones are responsible for color detection and work well in bright light, while rods work well in dim light but can't detect colors.
• The retina has a mostly yellow spot with cones and rods scattered throughout.

Eye Defects and Effects

• Shortsightedness: can't see far objects clearly due to a lens that is too thick or an eyeball that is too long.
• Longsightedness: can't see near objects clearly due to a lens that is too thin or an eyeball that is too short.
• Cataract: blurred vision due to age, long exposure to sunlight, or diabetes, and can be treated with artificial lens replacement.
• Astigmatism: can be treated with glasses or contact lenses.
• Color-blindness: inability to distinguish colors due to defects or absence of cones.

Eye Care Tips

• Maintain good posture and proper lighting when reading or using electronic devices.
• Keep a safe reading distance and use a clean towel to wash your face.
• Regular eye checks can help correct eye defects.
• Wear hats and sunglasses with UV protection to prevent strong light from damaging the eyes.
• Rest your eyes after reading or using electronic devices by looking at distant objects.

Hearing and Sound

• Sound is produced by the vibration of objects, which compresses air particles.
• Loudness is measured in decibels (dB), with higher amplitudes resulting in louder sounds.
• Pitch is determined by the frequency of sound waves, with higher frequencies resulting in higher-pitched sounds.
• Vocal cords in the throat produce sound when air is forced out through a slit.

Sound Travel

• Sound can travel through solid, gas, and liquid mediums, but not in a vacuum.
• Bionic ears can be treated with cochlear implants that transmit signals to the auditory nerve.

Ear Structure and Function

• The pinna collects sound waves and directs them into the ear canal.
• The eardrum vibrates from sound waves, transmitting signals to the brain.
• The cochlea is responsible for interpreting sound signals.

Hearing Loss and Noise Pollution

• Unpleasant or harmful sounds can lead to noise pollution and hearing loss.
• Noises above 85dB can cause permanent hearing loss, while long-term exposure to noises above 75dB can cause hearing loss.

Ear Care Tips

• Listen to music on earphones at no more than 60% of the maximum volume.
• Wear ear protectors in places with loud noises.
• Rest your ears after exposure to loud noises.
• See a doctor for a hearing check if you have signs of hearing loss.

Smell and Taste

• Smell receptors are stimulated by chemicals in the air, which are carried into the nose and dissolved in a moist layer.

• Smell receptors produce signals that are carried to the brain to be interpreted.

• Taste receptors are located on the tongue and are stimulated by chemicals in food that dissolve in saliva.

• Taste receptors produce signals that are carried to the brain to be interpreted.### Sense Organs

• The mouth has taste receptors on taste buds that are stimulated by dissolved chemicals, sending signals to the brain to be interpreted.

• There are 5 primary tastes: sweet, sour, salty, bitter, and umami.

• Chemicals in food can travel through the air into the nose when chewed, contributing to the sense of flavor.

• The skin has 5 kinds of receptors: pressure, heat, cold, pain, and touch, which are stimulated when in contact with a stimulus.

Brain Functions

• The brain receives signals from sensory receptors and interprets them to produce a response.
• The cerebrum controls the right body, learns, and memorizes.
• The cerebellum coordinates muscles, interprets signals, and understands movement.
• The medulla helps the body maintain balance, controls heartbeat, and breathing.

Addiction and Harmful Effects

• Drugs can harm our health by affecting sensory function and brain damage.
• Addictive substances can cause permanent damage to the heart, lungs, liver, and kidneys.
• Harmful effects include sores on the skin, addiction, hallucinations, loss of body control, and slow reaction.
• Frequent and painful urination, blurred vision, and permanent damage to the heart, lungs, liver, and kidneys are also possible.

Acids and Alkalis

• Acids are sour, corrosive, and can irritate the skin, while alkalines are bitter and slippery.
• Examples of acids include hydrochloric acid, nitric acid, and citric acid, while alkalines include sodium and potassium hydroxides.
• Safety precautions when using acids and alkalis in the lab include reading hazard labels, wearing safety goggles, wearing protective gloves, and avoiding direct contact.

Indicator and pH Meter

• Natural indicators like red cabbage, red carnation, and onion skin can be used to identify acidic or alkaline substances.
• Litmus paper and pH paper can also be used to test for acidity or alkalinity.
• Universal indicators can show the acidity or alkalinity of a solution.
• pH meters and pH sensors can provide precise measurements of pH levels.

Neutralization

• Acids and alkalis can be mixed together to cancel out their properties, resulting in neutralization.
• The pH curve can be used to determine the point of neutralization.
• Heat is released during neutralization, and the pH of the resulting solution is dependent on the volume of the reactants.

Applications

• Acid and alkali can be used to treat various conditions, such as tooth decay, wasp stings, and stomachaches.
• Industrial waste can be treated using acid and alkali.
• Acid and alkali can be used to clean surfaces and remove stains.
• Acid and alkali can corrode materials, but this can be prevented using protective coatings.