Physics basics
59 flashcards covering Physics basics for the ACT Science section.
Physics basics cover the fundamental principles of how the physical world operates, focusing on concepts like motion, forces, energy, and simple laws such as gravity and Newton's rules. For someone new to the subject, think of it as exploring why objects move, how energy transforms, and what keeps things in balance—building a foundation for understanding everyday phenomena and more complex ideas in science.
On the ACT Science section, physics questions typically appear in data interpretation passages, experimental setups, or hypothesis evaluations, often involving graphs, tables, or scenarios with variables like speed and force. Common traps include misreading trends in data or confusing similar concepts like velocity and acceleration, so focus on applying basic principles to real-world problems and identifying relationships in experiments. A key strategy is to practice sketching quick diagrams for motion problems.
Terms (59)
- 01
Speed
Speed is the scalar quantity that measures how fast an object is moving, calculated as the total distance traveled divided by the time taken.
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Velocity
Velocity is the vector quantity that includes both the speed of an object and its direction of motion.
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Acceleration
Acceleration is the rate of change of velocity over time, which can indicate speeding up, slowing down, or changing direction.
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Displacement
Displacement is the straight-line distance from the initial to the final position of an object, including direction.
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Distance
Distance is the total path length traveled by an object, regardless of direction.
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Newton's First Law
Newton's First Law states that an object at rest stays at rest, and an object in motion stays in motion at a constant velocity, unless acted upon by an unbalanced force.
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Newton's Second Law
Newton's Second Law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass, expressed as F = ma.
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Newton's Third Law
Newton's Third Law states that for every action, there is an equal and opposite reaction, meaning forces always occur in pairs.
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Force
Force is any interaction that, when unopposed, changes the motion of an object, measured in newtons.
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Mass
Mass is the amount of matter in an object, which determines its inertia and remains constant regardless of location.
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Weight
Weight is the force exerted on an object due to gravity, calculated as mass times gravitational acceleration.
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Gravity
Gravity is the force of attraction between two masses, responsible for objects falling toward Earth and planetary orbits.
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Friction
Friction is the force opposing motion when two surfaces are in contact, which can convert kinetic energy into heat.
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Inertia
Inertia is the tendency of an object to resist changes in its state of motion, as described in Newton's First Law.
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Work
Work is the energy transferred to or from an object via a force along a displacement, calculated as force times distance times the cosine of the angle between them.
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Energy
Energy is the capacity to do work or cause change, existing in forms like kinetic, potential, and thermal.
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Kinetic Energy
Kinetic energy is the energy an object possesses due to its motion, given by the formula KE = 1/2 mv^2, where m is mass and v is velocity.
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Potential Energy
Potential energy is the stored energy an object has due to its position or configuration, such as gravitational potential energy near Earth's surface.
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Conservation of Energy
The conservation of energy principle states that energy cannot be created or destroyed, only transformed from one form to another in a closed system.
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Power
Power is the rate at which work is done or energy is transferred, calculated as work divided by time, measured in watts.
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Momentum
Momentum is the product of an object's mass and velocity, a vector quantity that is conserved in isolated systems during collisions.
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Impulse
Impulse is the change in momentum of an object, equal to the force applied multiplied by the time interval over which it acts.
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Wave
A wave is a disturbance that transfers energy through a medium or space without transferring matter.
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Frequency
Frequency is the number of waves passing a point per second, measured in hertz, and determines the pitch of sound waves.
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Wavelength
Wavelength is the distance between successive crests or troughs of a wave, which affects its energy and speed.
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Amplitude
Amplitude is the maximum displacement of a wave from its equilibrium position, influencing the wave's intensity or loudness.
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Speed of Sound
The speed of sound is the rate at which sound waves travel through a medium, depending on the medium's density and elasticity, typically around 343 m/s in air at room temperature.
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Electric Current
Electric current is the flow of electric charge, typically electrons, through a conductor, measured in amperes.
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Voltage
Voltage, or electric potential difference, is the energy per unit charge provided to move charges through a circuit, measured in volts.
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Resistance
Resistance is the opposition to the flow of electric current in a material, depending on the material's properties and length, measured in ohms.
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Ohm's Law
Ohm's Law states that the current through a conductor is directly proportional to the voltage and inversely proportional to the resistance, expressed as I = V/R.
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Series Circuit
A series circuit is an electrical circuit where components are connected end-to-end, so the same current flows through all, but voltage divides among them.
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Parallel Circuit
A parallel circuit is an electrical circuit where components are connected across common points, allowing the same voltage across each but dividing the current.
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Magnetism
Magnetism is the phenomenon by which materials exert attractive or repulsive forces on other materials, often due to moving electric charges.
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Electromagnetic Induction
Electromagnetic induction is the process of generating an electric current by changing magnetic fields, as in generators or transformers.
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Heat
Heat is the transfer of thermal energy from a hotter object to a cooler one, often due to temperature differences.
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Temperature
Temperature is a measure of the average kinetic energy of the particles in a substance, indicating how hot or cold it is.
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Specific Heat
Specific heat is the amount of heat energy required to raise the temperature of one unit mass of a substance by one degree Celsius.
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First Law of Thermodynamics
The First Law of Thermodynamics states that the total energy of an isolated system is conserved, meaning energy added as heat or work equals energy gained or lost.
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Second Law of Thermodynamics
The Second Law of Thermodynamics states that heat cannot flow from a colder body to a hotter one without work being done, and entropy tends to increase.
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Density
Density is the mass per unit volume of a substance, which helps determine whether an object will float or sink in a fluid.
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Pressure
Pressure is the force exerted per unit area, such as atmospheric pressure or the pressure in a fluid, measured in pascals.
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Buoyancy
Buoyancy is the upward force exerted by a fluid on an immersed object, equal to the weight of the fluid displaced.
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Archimedes' Principle
Archimedes' Principle states that the buoyant force on an object equals the weight of the fluid it displaces, explaining why objects float or sink.
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Simple Machines
Simple machines are basic devices like levers and pulleys that multiply force or change its direction to make work easier.
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Torque
Torque is the rotational equivalent of force, calculated as force times the distance from the pivot point, causing an object to rotate.
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Equilibrium
Equilibrium is the state where the net force and net torque on an object are zero, so it remains at rest or moves at constant velocity.
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Vectors
Vectors are quantities with both magnitude and direction, such as velocity or force, and can be added using graphical or component methods.
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Scalars
Scalars are quantities that have only magnitude, such as mass or speed, without any direction.
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Projectile Motion
Projectile motion is the curved path an object follows when thrown near the Earth's surface, combining horizontal and vertical motion under gravity.
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Free Fall
Free fall is the motion of an object where gravity is the only force acting, resulting in constant acceleration downward.
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Uniform Circular Motion
Uniform circular motion is the movement of an object at a constant speed along a circular path, requiring a centripetal force.
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Centripetal Force
Centripetal force is the net force that keeps an object moving in a circular path, directed toward the center of the circle.
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Gravitational Force
Gravitational force is the attractive force between two masses, decreasing with the square of the distance between them, as per Newton's law of universal gravitation.
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Hooke's Law
Hooke's Law states that the force exerted by a spring is proportional to its displacement from equilibrium, expressed as F = -kx.
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Elasticity
Elasticity is the property of a material to return to its original shape after a deforming force is removed, as seen in springs.
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Reflection
Reflection is the bouncing back of a wave or light ray from a surface, following the law of reflection where angle of incidence equals angle of reflection.
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Refraction
Refraction is the bending of a wave as it passes from one medium to another, due to a change in speed, such as light entering water.
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Snell's Law
Snell's Law describes how light refracts at the boundary between two media, stating that the ratio of sines of angles equals the ratio of indices of refraction.