Newtons laws
59 flashcards covering Newtons laws for the MCAT Chem / Phys / Psych / Soc section.
Newton's laws are three foundational principles in physics that explain how objects move and interact with forces. The first law, often called the law of inertia, states that an object will remain at rest or in uniform motion unless an external force acts on it. The second law relates force, mass, and acceleration through the equation F=ma, showing that the force applied to an object determines how its motion changes. The third law describes how forces come in pairs, meaning every action produces an equal and opposite reaction. These laws form the basis for understanding everyday motion, from a ball rolling to the mechanics of the human body.
On the MCAT, Newton's laws frequently appear in the Chemical and Physical Foundations section, often in questions testing your ability to apply them to biological scenarios, such as blood flow or joint movements. Expect multiple-choice problems that involve calculations, like determining net forces, as well as conceptual questions about equilibrium or acceleration. Common traps include overlooking friction or misidentifying action-reaction pairs, so focus on drawing free-body diagrams and practicing real-world applications to avoid errors.
A concrete tip: Always identify all forces acting on an object before solving.
Terms (59)
- 01
Newton's First Law
An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction, unless acted upon by an unbalanced force.
- 02
Inertia
The tendency of an object to resist changes in its state of motion, as described by Newton's First Law.
- 03
Net Force
The vector sum of all forces acting on an object; if zero, the object is in equilibrium or moving at constant velocity per Newton's First Law.
- 04
Newton's Second Law
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.
- 05
Force
A push or pull that can cause an object to accelerate, as quantified in Newton's Second Law.
- 06
Mass
A measure of an object's inertia, which determines how much it resists acceleration when a force is applied, according to Newton's Second Law.
- 07
Acceleration
The rate of change of velocity of an object, directly related to the net force and inversely to mass via Newton's Second Law.
- 08
F = ma Formula
The mathematical expression of Newton's Second Law, where force equals mass times acceleration, used to calculate one variable when others are known.
- 09
Units of Force
Force is measured in newtons (N), where 1 N equals 1 kg·m/s², derived from the F = ma equation.
- 10
Newton's Third Law
For every action, there is an equal and opposite reaction, meaning forces always occur in pairs acting on different objects.
- 11
Action-Reaction Pair
Two forces that are equal in magnitude, opposite in direction, and act on different objects, as per Newton's Third Law.
- 12
Free-Body Diagram
A diagram that shows all forces acting on a single object, essential for applying Newton's Laws to analyze motion.
- 13
Friction Force
A force that opposes motion between two surfaces in contact, often requiring consideration in Newton's Second Law problems.
- 14
Static Friction
The force that prevents an object at rest from starting to move, up to a maximum value based on the coefficient of static friction.
- 15
Kinetic Friction
The force that opposes the motion of an object already sliding, generally less than the maximum static friction.
- 16
Coefficient of Friction
A dimensionless value that indicates the roughness between two surfaces, used in calculating friction forces in Newton's Laws.
- 17
Normal Force
The perpendicular force exerted by a surface on an object in contact with it, balancing other forces like gravity in equilibrium.
- 18
Tension
The force transmitted through a string or rope, analyzed using Newton's Second Law in systems like pulleys.
- 19
Gravitational Force
The attractive force between two masses, such as an object's weight, which is mg and acts downward.
- 20
Weight
The force due to gravity on an object, calculated as mass times gravitational acceleration, affecting motion via Newton's Laws.
- 21
Apparent Weight
The normal force experienced by an object, which can differ from actual weight in accelerating frames, like elevators.
- 22
Inclined Plane
A sloped surface where forces are resolved into components parallel and perpendicular to the slope for applying Newton's Laws.
- 23
Resolving Forces
Breaking down a force into components along specific axes, necessary for solving problems on inclined planes using Newton's Laws.
- 24
Atwood's Machine
A system of two masses connected by a string over a pulley, where Newton's Second Law is used to find acceleration.
- 25
Pulley Systems
Arrangements that change the direction of tension forces, analyzed with Newton's Laws to determine net forces and motion.
- 26
Centripetal Force
The net force directed toward the center of a circular path, provided by other forces and explained by Newton's Laws.
- 27
Common Mistake: Ignoring Air Resistance
Forgetting that air resistance acts as an additional force, which can alter the predicted motion from ideal Newton's Law applications.
- 28
Strategy for Force Problems
Identify all forces, draw a free-body diagram, apply Newton's Second Law in each direction, and solve for unknowns systematically.
- 29
Equilibrium
A state where the net force on an object is zero, resulting in no acceleration, as per Newton's First and Second Laws.
- 30
Static Equilibrium
When an object is at rest and all forces balance, requiring the sum of forces and torques to be zero.
- 31
Hooke's Law
The force exerted by a spring is proportional to its displacement, F = -kx, and can be combined with Newton's Second Law.
- 32
Elastic Forces
Forces from deformed objects like springs, which follow Hooke's Law and affect motion per Newton's Laws.
- 33
Buoyant Force
The upward force on an object immersed in a fluid, equal to the weight of the displaced fluid, analyzed with Newton's Laws.
- 34
Drag Force
A resistive force from a fluid, opposing motion and depending on speed, which must be considered in real-world Newton's Law scenarios.
- 35
Terminal Velocity
The constant speed reached when drag force equals gravitational force, resulting in zero net force per Newton's First Law.
- 36
Impulse
The change in momentum of an object, equal to force times time, derived from Newton's Second Law.
- 37
Conservation of Momentum
In a closed system, total momentum remains constant if no external forces act, as implied by Newton's Third Law in collisions.
- 38
Elastic Collision
A collision where kinetic energy is conserved, analyzed using conservation of momentum and Newton's Laws.
- 39
Inelastic Collision
A collision where kinetic energy is not conserved, but momentum is, per Newton's Third Law.
- 40
Elevator Problem Example
In an accelerating elevator, the apparent weight changes based on the elevator's acceleration, applying Newton's Second Law.
- 41
Block on a Ramp Example
For a block sliding down an incline, resolve gravity into components and use Newton's Second Law to find acceleration.
A 2 kg block on a 30-degree ramp with coefficient of kinetic friction 0.3 has net force mg sin θ - friction, yielding acceleration of about 2.5 m/s².
- 42
Misconception: Force Equals Velocity
Force causes acceleration, not velocity, so applying Newton's Second Law requires distinguishing between the two.
- 43
Vector Nature of Forces
Forces are vectors with magnitude and direction, so they must be added vectorially when applying Newton's Laws.
- 44
Resultant Force
The single force that has the same effect as all combined forces, used in Newton's Second Law calculations.
- 45
Weightlessness
The sensation in free fall where apparent weight is zero, explained by Newton's Laws in accelerating frames.
- 46
Newton's Laws in Circular Motion
Centripetal acceleration requires a net force toward the center, as per Newton's Second Law.
- 47
Common Trap: Equal Masses Equal Acceleration
In systems like Atwood's machine, acceleration depends on mass difference, not just equality.
- 48
Frictionless Surfaces
Ideal scenarios with no friction, simplifying Newton's Law applications to focus on other forces.
- 49
Advanced: Variable Mass Systems
Systems where mass changes, like rockets, requiring modified application of Newton's Second Law.
- 50
Torque and Newton's Laws
Rotational equivalent of force, related to angular acceleration, extending Newton's Second Law to rotation.
- 51
Moment of Inertia
The rotational analog of mass, affecting angular acceleration in Newton's Second Law for rotation.
- 52
Pseudoforce in Non-Inertial Frames
An apparent force in accelerating frames, like a car turning, to apply Newton's Laws correctly.
- 53
Worked Example: Two Blocks Connected
For two blocks connected by a string on a horizontal surface, apply Newton's Second Law to each and solve the system.
If a 3 kg block pulls a 2 kg block with 10 N force and friction is negligible, the acceleration is 2 m/s².
- 54
Strategy for Inclined Plane Problems
Resolve gravity, identify friction, set up equations using Newton's Second Law for both directions.
- 55
Advanced: Relativistic Limits
At high speeds, Newton's Laws approximate but deviate; MCAT focuses on classical applications.
- 56
Common Error: Forgetting Reaction Forces
In interactions, always pair forces as per Newton's Third Law to avoid incomplete analysis.
- 57
Galilean Relativity
Newton's Laws hold in inertial frames, meaning laws are the same for observers moving at constant velocity.
- 58
Application to Satellites
Orbital motion as a balance of gravitational force and centripetal force per Newton's Laws.
- 59
Escape Velocity
The minimum speed to escape gravity, derived from energy considerations but rooted in Newton's Laws.