Physic Basic Flashcards
State Newton’s First Law of Motion briefly.
An object remains at rest or in uniform motion unless acted on by an external force.
Write the formula for average velocity.
v_avg = (Δx)/(Δt).
If acceleration is constant, what is the formula for final velocity v given initial velocity v₀ and acceleration a over time t?
v = v₀ + a·t.
Formula for displacement under constant acceleration, starting from rest?
x = (1/2) a t².
State Newton’s Second Law in a formula.
F = m·a.
Write the formula for weight (on Earth’s surface).
W = m·g.
What does g typically approximate near Earth’s surface?
9.8 m/s².
State the formula for frictional force for kinetic friction.
F_f = μ_k N (where N is normal force).
What is centripetal acceleration formula for uniform circular motion?
a_c = v²/r.
State Newton’s Third Law of Motion.
For every action, there is an equal and opposite reaction.
Formula for momentum p of a mass m with velocity v?
p = m·v.
What is impulse defined as?
Change in momentum (Δp), or Force × time interval.
In an inelastic collision, which quantity is conserved: momentum, kinetic energy, or both?
Momentum is conserved, kinetic energy is not.
What is the formula for centripetal force for uniform circular motion?
F_c = m·v²/r.
Define uniform acceleration in terms of velocity.
Velocity changes at a constant rate over time.
If a projectile is launched horizontally at speed v, ignoring air resistance, how does its horizontal velocity change?
Remains constant (no horizontal acceleration).
If a projectile is launched straight up with speed v₀, ignoring air resistance, what is its speed at the top of its path?
0 m/s (instantaneously).
What is terminal velocity in free fall with air resistance?
The constant velocity where drag force = weight.
According to Newton’s law of universal gravitation, F_g=?
F_g=G(m₁m₂)/r².
On an inclined plane with angle θ, ignoring friction, acceleration of a block down the slope is?
g sinθ.
Define Work in physics, W=?
W=F·d·cos(θ) (force × displacement × cos of angle).
Kinetic Energy (KE) formula for mass m moving at speed v?
KE = (1/2)m v².
Potential Energy (PE) near Earth’s surface with mass m at height h?
PE = m g h.
Law of Conservation of Energy in closed system states…?
Total energy remains constant (KE + PE + other forms = constant).
Work-Energy Theorem in short form?
Net Work done = ΔKinetic Energy.
Power P is defined as?
Work done per unit time: P = W / t.
SI unit of Work or Energy is…?
Joule (J).
SI unit of Power is…?
Watt (W), i.e. Joule per second.
Mechanical advantage of a simple machine concept?
Ratio of output force to input force.
Formula for elastic potential energy in a spring (Hooke’s Law) with constant k?
PE_spring= (1/2)k x².
Hooke’s Law for spring force, F_s=?
F_s=−k x (restoring force).
Gravitational potential energy between masses (Newton’s universal)? (In general form)
U=−G(m₁m₂)/r.
If an object’s speed doubles, its kinetic energy changes by factor of…?
4 (since KE∝v²).
Work done by friction is positive or negative if motion is opposite direction of friction?
Negative.
If no friction, total mechanical energy is constant: T/F?
True.
Potential energy stored in an elevated mass is mgh. Doubling height does what to potential energy?
Doubles it.
Scalar or vector? Work is a…?
Scalar.
Calculate power if 100 J of work is done in 5 s.
Power=100/5=20 W.
One horsepower is about 746 watts: T/F?
True.
If Net Work=0, how does speed change?
It doesn’t change (no change in KE).
Momentum p= m·v. If both mass and velocity double, momentum changes by factor…?
4.
Impulse J=F·Δt. Also equals Δp, T/F?
True.
In an elastic collision, which two quantities are conserved?
Momentum and kinetic energy.
Unit of momentum in SI?
kg·m/s.
If total external force on a system = 0, total momentum is…?
Constant (conserved).
If two masses stick together after collision, it’s called…?
Perfectly inelastic collision.
State the formula for ballistic pendulum or typical inelastic collision in short.
m₁v₁ + m₂v₂= (m₁+m₂)v_final.
If object’s momentum is zero, is speed definitely zero?
Yes, if mass is not zero.
Time to stop an object with certain impulse is shorter if force is bigger or smaller?
Bigger force => shorter time.
Collision with identical masses in a 1D elastic scenario: if one is at rest, the moving mass stops, the other moves with same speed. T/F?
True (the classic Newton’s cradle effect).
Define frequency f in terms of period T?
f=1/T.
Wave speed v=?
v= λ f (wavelength×frequency).
Hooke’s Law for a simple harmonic oscillator: F=?
F=−kx (restoring force).
Period of a simple pendulum (small angles) T=?
T=2π√(L/g).
Period of a mass-spring system T=?
T=2π√(m/k).
The amplitude of a wave is the maximum displacement from equilibrium. T/F?
True.
In a transverse wave, the medium vibrates perpendicular to wave direction. T/F?
True.
In a longitudinal wave, the medium vibrates parallel to wave direction. T/F?
True.
Resonance occurs when driving frequency = natural frequency. T/F?
True.
Sound is typically a longitudinal wave in air, T/F?
True.
Zeroth Law of Thermodynamics states…?
If A is in thermal equilibrium with B, and B with C, then A and C are in equilibrium.
First Law of Thermodynamics formula?
ΔU= Q−W (change in internal energy= heat in−work out).
Second Law of Thermodynamics in short?
Entropy of an isolated system never decreases.
Define temperature in a basic sense.
Measure of average kinetic energy of particles.
Heat conduction formula (Fourier’s Law) in short?
Q/t= kA (ΔT/Δx).
SI unit of heat or energy is the Joule: T/F?
True.
Define specific heat capacity c.
Amount of heat needed to raise 1 kg of a substance by 1°C.
In isobaric process, pressure is constant. T/F?
True.
In an adiabatic process, what is Q?
Q=0 (no heat exchange).
At phase change (e.g. melting), temperature remains constant as energy changes phase: T/F?
True.
Coulomb’s Law for electrostatic force F=?
F= k (q₁ q₂)/r².
Value of Coulomb’s constant k≈?
8.99×10⁹ N·m²/C².
Electric field E due to point charge Q at distance r=?
E= k Q/r².
Definition: Electric current I=?
Charge flow per unit time: I=ΔQ/Δt.
Ohm’s Law formula?
V= I R.
SI unit of Resistance is…?
Ohm (Ω).
In series circuit, how do we add resistances R?
R_total=R₁+R₂+….
In parallel circuit, how do we add resistances?
1/R_total=1/R₁+1/R₂+….
SI unit of electric charge is…?
Coulomb (C).
Definition of electric power P?
P= I V= I² R= V²/R.
Magnetic force on a moving charge q with velocity v in magnetic field B, F=?
F= q v B sin(θ).
Right-hand rule for magnetic force if charge is positive: T/F?
True, use right-hand rule for direction.
Gauss’s Law for electric fields: ∮ E · dA=?
Q_enc/ε₀.
Ampere’s Law in magnetism: ∮ B · dl=?
μ₀ I_enc (for steady currents).
Faraday’s Law of Induction in short?
EMF=−dΦ/dt (negative sign is Lenz’s Law).
Lenz’s Law indicates the induced current direction does what?
Opposes the change in magnetic flux.
Capacitance of parallel-plate capacitor: C=?
ε₀ (A/d).
Energy stored in a capacitor formula, U=?
U= (1/2) C V².
Definition of electromotive force (emf) concept?
Voltage provided by a source (like battery).
If a circuit has resistance R and supply V, then I=?
I= V/R.
Speed of light in vacuum c≈?
3×10⁸ m/s.
Einstein’s mass-energy equivalence formula?
E= m c².
Photoelectric effect main formula?
K_max= h f − φ (work function).
Planck’s constant h≈?
6.626×10⁻³⁴ J·s.
Definition of half-life t₁/₂ in radioactivity?
Time for half of a radioactive sample to decay.
Bohr model for hydrogen: electron orbits with quantized angular momentum T/F?
True.
Heisenberg’s Uncertainty Principle in short?
Δx Δp ≥ ħ/2.
De Broglie wavelength λ=?
λ= h/p= h/(m v).
Thermal radiation peak shifts with temperature (Wien’s Law) T/F?
True, λ_peak∝1/T.
Definition: Mach number=?
Object speed / speed of sound in medium.
Define displacement in kinematics.
The net change in position from an initial point to a final point, a vector quantity.
Define speed in physics.
The rate of distance traveled per unit time, a scalar quantity (no direction).
Define velocity.
Displacement per unit time, a vector quantity with magnitude and direction.
Define acceleration.
The rate of change of velocity over time.
Define inertia.
The property of an object to resist changes in its state of motion.
Define net force.
The vector sum of all forces acting on an object.
Define equilibrium (mechanical).
State where net force on an object is zero, so its acceleration is zero.
Define normal force.
Perpendicular contact force exerted by a surface on an object.
Define friction force.
A resistive force that opposes relative motion between surfaces in contact.
Define terminal velocity.
Constant velocity reached by a falling object when drag force equals weight.
Define momentum.
Product of mass and velocity (p = m·v), a vector.
Define impulse.
Change in momentum, or force multiplied by the time interval (Δp).
Define collision (in physics).
An event where two or more bodies exert forces on each other in a relatively short time.
Define elastic collision.
A collision where total kinetic energy and momentum are both conserved.
Define inelastic collision.
A collision where momentum is conserved but kinetic energy is not.
Define work (physics definition).
Force applied over a distance in the direction of displacement (W=F·d·cosθ).
Define power (physics).
The rate at which work is done or energy is transferred (P=W/t).
Define kinetic energy.
Energy due to an object’s motion, (1/2)mv².
Define potential energy.
Stored energy based on position or configuration (e.g., mgh for gravity).
Define mechanical energy.
Sum of kinetic and potential energies in a system.
Define efficiency (of a machine).
Ratio of useful work output to total energy input, typically a percentage.
Define amplitude (in waves or oscillations).
Maximum displacement from equilibrium position.
Define period (wave or oscillation).
Time for one complete cycle or oscillation.
Define frequency (waves).
Number of oscillations or cycles per unit time (f=1/T).
Define wavelength (λ).
Distance between consecutive identical points (e.g., crest to crest) in a wave.
Define transverse wave.
A wave where the medium’s displacement is perpendicular to wave propagation direction.
Define longitudinal wave.
A wave where the medium’s displacement is parallel to wave propagation direction (e.g., sound).
Define resonance.
A phenomenon where a system oscillates at maximum amplitude at its natural frequency.
Define node (in a standing wave).
Point of zero amplitude where destructive interference is consistent.
Define antinode (in a standing wave).
Point of maximum amplitude where constructive interference is consistent.
Define temperature in thermodynamics.
A measure of average kinetic energy of the particles in a substance.
Define internal energy (U) of a system.
The total microscopic kinetic and potential energies of all particles in a system.
Define heat (Q).
Thermal energy transfer from one body to another due to temperature difference.
Define specific heat capacity.
Amount of heat needed to raise 1 kg of a substance by 1°C (or 1 K).
Define latent heat.
Heat required for a phase change without temperature change.
Define conduction (heat transfer).
Transfer of heat via direct molecular collisions within a material.
Define convection (heat transfer).
Transfer of heat via fluid motion (e.g., warm air rising).
Define radiation (heat transfer).
Transfer of heat through electromagnetic waves (no medium needed).
Define entropy.
A measure of disorder or randomness in a system.
Define isothermal process.
Thermodynamic process at constant temperature.
Define electric charge.
A fundamental property (positive or negative) that causes electromagnetic interactions.
Define electric field E.
Region around a charge where another charge experiences force (E=F/q).
Define electric potential (V).
Electric potential energy per unit charge at a point in an electric field.
Define capacitor.
Device that stores electric charge and energy in an electric field.
Define electric current (I).
The rate of flow of electric charge, measured in Amperes (A).
Define resistance (R).
Opposition to current flow in a conductor, measured in ohms (Ω).
Define magnetic field B.
A field surrounding moving charges or magnetic materials that exerts force on other charges or magnets.
Define electromagnetic induction.
Creation of an EMF (voltage) by changing magnetic flux through a circuit.
Define transformer (in AC circuits).
Device that changes voltage levels via electromagnetic induction between coils.
Define photon (in modern physics).
A quantum of electromagnetic radiation, carrying energy E=hf.
Kinematic equation for constant acceleration: final velocity v?
v = v₀ + a t
Kinematic equation for displacement under constant acceleration (from rest)?
x = (1/2) a t²
Kinematic equation: x − x₀ = v₀ t + (1/2) a t²?
Yes, for constant acceleration, general form of displacement.
Another kinematic formula: v² = v₀² + 2a(x − x₀)?
Yes, relates velocities, acceleration, and displacement.
Newton’s Second Law in formula form?
F_net = m a
Friction force for kinetic friction?
F_f = μ_k N
Friction force for static friction (max)?
F_f(max)= μ_s N
Weight near Earth’s surface: W=?
m g (g≈9.8 m/s²)
Centripetal acceleration formula a_c=?
a_c= v² / r
Centripetal force formula F_c=?
F_c= m (v²/r) (points radially inward)
Impulse formula: J=?
J= F Δt= Δp (change in momentum)
Momentum p=?
p= m v
Work done by constant force: W=?
W= F d cos(θ)
Kinetic energy: KE=?
(1/2) m v²
Gravitational potential energy near Earth: PE=?
m g h
Spring potential energy: PE_spring=?
(1/2) k x²
Hooke’s Law for spring force: F_s=?
−k x
Power: P=?
Work / time = (W/t)= F v (if force and velocity parallel)
Mechanical energy (no friction): E=?
E= KE + PE= constant (if no nonconservative forces)
Momentum conservation formula in collisions?
m₁v₁ + m₂v₂= m₁v₁’ + m₂v₂’ (assuming no external net force)
Period of a simple pendulum (small angle): T=?
T= 2π √(L/g)
Period of a mass-spring oscillator: T=?
T= 2π √(m/k)
Wave speed formula: v=?
v= λ f (wavelength × frequency)
Snell’s Law for refraction: n₁ sinθ₁=?
n₂ sinθ₂
Doppler effect for sound (source stationary, observer moving): f’=?
f’ = (v ± v_obs)/(v) × f (sign depends on direction)
Universal law of gravitation: F=?
G (m₁ m₂)/ r²
Orbital velocity for satellite near Earth: v=?
v= √(GM/r)
Torque formula τ=?
τ= r F sin(θ), or lever arm × force
Moment of inertia of a point mass about an axis: I=?
I= m r²
Rotational kinetic energy: K_rot=?
(1/2) I ω² (where I is moment of inertia, ω is angular velocity)
Angular momentum L for a point mass: L=?
L= I ω= m r² ω or r × p in vector form
Work-Energy Theorem: W_net=?
ΔK (change in kinetic energy)
Bernoulli’s Equation (ideal fluid): P + (1/2)ρv² + ρg h=?
constant along a streamline
Continuity equation (incompressible fluid): A v=?
constant (A is cross-section, v is fluid speed)
Ideal Gas Law: PV=?
n R T
Boyle’s Law (T constant): P₁V₁=?
P₂V₂
Charles’s Law (constant P): V₁/T₁=?
V₂/T₂
Thermodynamic work by gas at constant pressure: W=?
P (ΔV)
Heat Q needed to change temperature: Q=?
m c ΔT (c is specific heat)
Latent heat formula for phase change: Q=?
m L (L= latent heat)
Electrical power formula: P=?
P= I V= I²R= V²/R
Ohm’s Law: V=?
I R
Resistance in series: R_total=?
R₁+R₂+…
Resistance in parallel: 1/R_total=?
1/R₁ + 1/R₂ +…
Electric field from a point charge Q at distance r: E=?
kQ/r² (k=8.99×10⁹ N·m²/C²)
Electric potential from point charge Q at distance r: V=?
kQ/r
Capacitance of parallel-plate capacitor: C=?
ε₀ (A/d)
Energy stored in a capacitor: U=?
(1/2) C V²
Magnetic force on charge q with velocity v in field B: F=?
q v B sin(θ)
Faraday’s Law of Induction: EMF=?
− dΦ_B / dt (where Φ_B is magnetic flux)
A car accelerates from rest at 2 m/s². After 5 seconds, what is its speed?
v = v₀ + at = 0 + (2)(5)= 10 m/s.
An object falls freely (no air resistance). After 3 seconds, how far has it fallen from rest?
Use x= (1/2)gt² => (1/2)(9.8)(3²)= (4.9)(9)= 44.1 m (approx).
A box is pulled across frictionless ice with 20 N force, mass=10 kg. Acceleration?
F= ma => a= F/m= 20/10= 2 m/s².
A 2 kg mass has velocity from 2 m/s to 4 m/s. Change in momentum?
Δp= m(v₂ − v₁)=2(4−2)=4 kg·m/s.
A 3.0 kg object has velocity 4 m/s. What’s its kinetic energy?
KE= (1/2)mv²= (1/2)(3)(16)=24 J.
You lift a 5 kg object by 2 m. How much potential energy gained?
ΔPE= mgh= 5×9.8×2= 98 J (approx).
A 6 N horizontal force moves an object 3 m. Work done?
W= F d=6×3=18 J.
An object’s velocity changes from 10 m/s to 6 m/s in 2 s. Average acceleration?
a=Δv/Δt= (6−10)/2= −2 m/s².
A block slides on friction. No friction means KE+PE constant. If it starts with 100 J, how much energy after some motion?
Still 100 J (conservation of mechanical energy).
A projectile is launched horizontally at 5 m/s from height 20 m. Ignoring air, how long does it take to hit ground?
Use vertical free-fall: t= √(2h/g)= √(40/9.8)≈√4.08≈2.02 s.
With the same projectile: horizontal distance traveled in that 2.02 s if v_x=5 m/s?
Range= v_x× t= 5×2.02=10.1 m (approx).
Tug of war: if teams pull equally with 100 N each, net force on rope?
0 N (forces cancel).
On Earth, a 10 kg mass weighs how many newtons?
W= mg= (10)(9.8)= 98 N.
If you push with 15 N on a frictionless object, it pushes you back with 15 N. Which law?
Newton’s Third Law.
If friction coefficient is 0.2, normal force 50 N, friction force?
f= μ N=0.2×50=10 N.
A 2 kg block on frictionless slope (30° from horizontal). Acceleration down slope?
a= g sin(30°)= 9.8×0.5= 4.9 m/s².
A bullet of mass 0.01 kg traveling 200 m/s hits a wall, stops. Change in momentum?
Δp=0.01(0−200)= −2 kg·m/s (magnitude 2).
An object’s momentum is 8 kg·m/s, mass=2 kg, find velocity.
v= p/m= 8/2=4 m/s.
What is the net work done if an object speeds from KE=5 J to KE=15 J?
W= ΔKE=15−5=10 J.
A 3 kg mass rests on the floor, how much potential energy w.r.t. floor?
PE=0 J if reference is floor (none).
Force of 10 N applied at angle 60° from horizontal, displacement 5 m horizontally. Work done?
W= F cosθ × d=10 cos60° ×5= (10×0.5)×5=25 J.
A mass on spring (k=100 N/m) is stretched by 0.2 m. Potential energy stored?
PE= (1/2) k x²= 0.5×100×(0.2)²= (50)(0.04)=2 J.
Frictionless roller coaster starts at 20 m high. If speed at bottom is v, ignoring friction, mg(20)= (1/2)mv². Solve for v.
v= √(2gh)= √(2×9.8×20)= √392≈19.8 m/s.
An elevator lifts 500 kg up 10 m in 20 s. How much power used ignoring friction?
Power= (mgh)/t= (500×9.8×10)/20= (49000)/20=2450 W.
A wave has frequency 5 Hz, wavelength 2 m. Wave speed?
v= λ f= (2)(5)=10 m/s.
Period of a 5 Hz wave?
T=1/f=1/5=0.2 s.
Pendulum length is 1 m. Small angle period?
T=2π√(L/g)= 2π√(1/9.8)=2π√(0.102)= approx 2π×0.319=2.0 s.
A 500 g mass moves at 4 m/s. Kinetic energy?
KE= (1/2)(0.5)(4²)= (0.25)(16)=4 J.
Capacitor of 10 µF at 12 V. Energy stored?
U= (1/2)CV²=0.5×(10×10⁻⁶)×(12²)= (5×10⁻⁶)×144=7.2×10⁻⁴ J.
Electric circuit with V=9 V, R=3 Ω. Current I=?
I= V/R=9/3=3 A.
Sound wave of speed 340 m/s, frequency 170 Hz. Wavelength?
λ= v/f= 340/170=2 m.
A force of 10 N acts on mass 2 kg for 2 s. Impulse J=?
J= F×t=10×2=20 N·s => Δp=20 kg·m/s.
If object’s momentum changes by 20 kg·m/s, mass=4 kg, velocity change?
Δv= Δp/m=20/4=5 m/s.
Falling from rest for 2 s, ignoring air, velocity?
v= gt= (9.8)(2)=19.6 m/s.
Projectile’s horizontal velocity if launched at 10 m/s, angle=0°, ignoring air?
Constant 10 m/s horizontally.
If friction is 5 N, distance=4 m, friction does how much negative work?
W= −F d= −(5)(4)=−20 J.
Current 2 A flows 10 s, total charge passed?
Q=I t= (2)(10)=20 C.
Parallel-plate capacitor, area=1 m², separation=0.01 m, ignoring dielectric. Capacitance?
C= ε₀(A/d)= (8.85×10⁻¹²)(1)/(0.01)=8.85×10⁻¹⁰ F.
Ohm’s Law: if R=4 Ω, and I=2 A, voltage needed?
V= IR= (2)(4)=8 V.
Ball on string, radius=1 m, speed=3 m/s. Centripetal acceleration?
a_c= v²/r= (3²)/1=9 m/s².
Energy to raise 1 kg water by 10°C. Specific heat c= 4184 J/kg·K => Q=?
Q= m c ΔT= (1)(4184)(10)= 41840 J.
Magnetic force on 2 C charge moving at 3 m/s in B= 1 T, velocity perpendicular => F=?
F= q v B= (2)(3)(1)=6 N.
Two 2 Ω resistors in series => total R=?
4 Ω.
Same two 2 Ω resistors in parallel => total R=?
1/(1/2+1/2)=1 Ω.
Light speed c=3×10⁸ m/s, frequency 6×10¹⁴ Hz => wavelength?
λ= c/f= (3×10⁸)/(6×10¹⁴)= 5×10⁻⁷ m (500 nm).
Sine wave amplitude 2 cm, frequency 10 Hz => period?
T=1/f=1/10=0.1 s.
Boyle’s Law: if P₁= 2 atm, V₁=2 L, new volume if pressure becomes 4 atm (constant T)?
P₁V₁= P₂V₂ => 2×2=4×V₂ => V₂=1 L.
Gravitational potential near Earth: U=mgh => if mass=10 kg, h=3 m => U=?
U= (10)(9.8)(3)=294 J.
An object at rest has momentum p=?
p=0 kg·m/s.
If mechanical advantage of a lever is 4, applying 10 N force => output?
40 N (ideally, ignoring friction).
