Fundamentals of Motion
Motion is the process of an object changing its location over time. Understanding how objects move is essential in various healthcare fields, including the interpretation of diagnostic imaging techniques like X-rays and MRIs, as well as the understanding of physiological processes like blood circulation.
Key Concepts:
- Speed: Refers to how fast an object moves, measured as the distance it travels in a given time frame.
Formula: Speed = Distance ÷ Time
Units: meters per second (m/s) or kilometers per hour (km/h) - Velocity: Describes the rate of an object’s position change in a specific direction.
Formula: Velocity = Displacement ÷ Time - Acceleration: Indicates the change in velocity over time, showing how quickly an object speeds up or slows down.
Formula: Acceleration = Change in velocity ÷ Time
Units: meters per second squared (m/s²)
Example:
If a car accelerates from 0 m/s to 20 m/s in 5 seconds, its acceleration would be calculated as:
Acceleration = (20 – 0) ÷ 5 = 4 m/s²
Newton’s Laws of Motion
Newton’s laws provide the foundation for understanding object movement, from the actions of muscles to the operation of medical instruments.
Key Concepts:
- First Law (Law of Inertia): An object will either remain stationary or continue in uniform motion unless an external force acts upon it.
- Second Law (F = ma): The force applied to an object is directly proportional to its mass and the acceleration produced.
Formula: F = ma
Units: Newtons (N) for force, kilograms (kg) for mass, meters per second squared (m/s²) for acceleration. - Third Law: Every action has an equal and opposite reaction.
Example:
A 5 kg cart is pushed with a force of 10 N. Its acceleration would be:
Acceleration = F ÷ m = 10 N ÷ 5 kg = 2 m/s²
Energy: Kinetic and Potential
Energy is the capacity to perform work. The two main forms of energy we’ll focus on are kinetic energy (the energy of motion) and potential energy (energy stored due to position or condition).
Key Concepts:
- Kinetic Energy (KE): The energy an object has because of its movement.
Formula: KE = 1/2 mv²
Units: Joules (J), where m is mass and v is velocity. - Potential Energy (PE): The stored energy of an object based on its position or condition.
Formula: PE = mgh
Where m is mass, g is gravitational acceleration (9.8 m/s²), and h is height.
Example:
If a 2 kg object is positioned 10 meters above the ground, its potential energy is:
PE = 2 kg × 9.8 m/s² × 10 m = 196 J
Work and Power
Work and power describe how energy is transferred or converted in a system.
Key Concepts:
- Work (W): Energy transferred when a force is applied to move an object.
Formula: W = F × d
Where F is force and d is displacement in the direction of the force. - Power (P): The rate at which work is performed or energy is transferred.
Formula: P = W ÷ t
Units: Watts (W), where W is work and t is time in seconds.
Example:
If 200 J of work is done over 10 seconds, the power is:
P = 200 J ÷ 10 s = 20 W
Heat and Thermodynamics
Thermodynamics is the field of science that explores how heat is transferred and how energy is converted between different forms. In healthcare, understanding thermodynamics is essential for managing body temperature, especially in conditions like fever or hypothermia.
Key Concepts:
- Heat: Energy that moves between substances due to a difference in temperature.
Units: Joules (J), calories (cal). - First Law of Thermodynamics: Energy cannot be created or destroyed; it can only be transferred or converted into another form.
Formula: ΔU = Q − W, where ΔU represents the change in internal energy, Q is the heat added, and W is the work done by the system. - Second Law of Thermodynamics: Entropy, or disorder, in a closed system tends to increase over time, leading to more disordered states.
Waves and Sound
Waves are disturbances that transfer energy through different mediums, and sound is a type of wave that moves through air (or other materials).
Key Concepts:
- Waves: A disturbance that carries energy through a medium. Waves can be mechanical, like sound waves, or electromagnetic, like light waves.
- Frequency (f): The number of wave cycles passing a given point each second.
Units: Hertz (Hz), where 1 Hz = 1 wave per second. - Sound Waves: Sound is a type of longitudinal wave that propagates through a medium, usually air. Its speed depends on factors like the type of medium and its temperature.
Example:
If the frequency of a sound wave is 1000 Hz, what is its period?
Formula: T = 1 / f = 1 / 1000 = 0.001 s
Light and Optics
Optics is the study of how light interacts with materials, which is important for medical imaging technologies such as X-rays and MRIs.
Key Concepts:
- Refraction: The bending of light when it moves from one medium to another, like from air into water.
- Reflection: When light bounces off a surface, such as a mirror.
- Lenses: Optical devices used to focus or spread light, found in tools like eyeglasses and microscopes.
Electricity and Magnetism
Electricity and magnetism are fundamental in modern medical devices, including electrocardiograms (EKGs), MRI scanners, and pacemakers.
Key Concepts:
- Electric Current: The flow of electric charge, typically measured in amperes (A).
- Voltage: The difference in electric potential between two points.
Formula: V = IR, where V is voltage, I is current, and R is resistance. - Magnetism: The force generated by magnets, which can either attract or repel one another.
- Ohm’s Law: Describes how voltage, current, and resistance are related in an electrical circuit.
Example:
For a circuit with a resistance of 10 ohms and a current of 2 A, what is the voltage?
Formula: V = IR = 2 × 10 = 20 V