Conceptual Physics Final Exam: Momentum, Energy, Waves, and Relativity

What is linear momentum?

Linear momentum (p) is defined as the product of mass (m) and velocity (v), represented as p = mv.

How is momentum related to velocity?

Momentum is a vector quantity that matches the direction of velocity.

What happens to the momentum of an object at rest?

If an object is at rest, its velocity is zero, and therefore its linear momentum is also zero (p = 0).

What is impulse?

Impulse (I) is the product of the average net force (F) exerted on an object and the time interval (Δt) during which that force acts, represented as I = FΔt.

What does the impulse-momentum theorem state?

The impulse applied to an object is equal to the change in its linear momentum: FΔt = Δp = mΔv.

How can you maximize momentum change?

To maximize momentum change, apply the maximum possible force for the longest possible duration.

What is the relationship between force and time when stopping an object?

Force and time are inversely proportional when stopping an object; extending the time of impact reduces the force.

What occurs when momentum is stopped in a brief time?

Stopping momentum in a very brief time results in an extremely high force exerted.

What is the critical exam trap regarding bouncing?

Bouncing requires greater impulse than merely stopping, delivering up to twice the force compared to an object that hits and sticks.

What does conservation of linear momentum state?

In the absence of external net forces, the total linear momentum of a system remains constant: ∑pbefore = ∑pafter.

What are elastic collisions?

In elastic collisions, objects bounce away perfectly, conserving both momentum and kinetic energy.

What are inelastic collisions?

In inelastic collisions, objects stick together or deform, conserving momentum but degrading mechanical kinetic energy into heat and sound.

What is mechanical work?

Mechanical work (W) is the transfer of energy through a mechanical process when a force acts on an object causing displacement, represented as W = Fd.

When is work done on an object?

Work is done when the force vector acts parallel to the displacement vector.

What is power in physics?

Power (P) is the rate at which work is performed or energy is transformed, measured in Watts (1 W = 1 J/s).

What is potential energy?

Potential energy (PE) is stored energy due to an object's position or elevation above a reference level, calculated as PE = mgh.

What is kinetic energy?

Kinetic energy (KE) is the energy of motion, calculated as KE = ½mv².

What is the velocity-squared non-linearity rule?

Because velocity is squared in the KE equation, doubling speed increases kinetic energy fourfold.

What does the work-energy theorem state?

The net work performed by external forces equals the change in kinetic energy: W = ΔKE.

What is the braking distance trap?

If a car travels three times faster, it requires nine times the skidding distance to stop due to increased kinetic energy.

What is the conservation of mechanical energy?

Energy cannot be created or destroyed; it can only transform, maintaining a constant total energy in an ideal mechanical system.

What is rotational inertia?

Rotational inertia (moment of inertia, I) represents an object's resistance to changes in its rotational state, depending on mass and its distribution relative to the axis of rotation.

What happens in the incline race scenario?

A solid cylinder will always win against a hollow hoop of identical mass and diameter when rolling down a ramp due to differences in rotational inertia.

What determines the rotational inertia of an object?

Both the total mass and how that mass is distributed relative to the axis of rotation.

In an incline race, which object rolls down faster: a solid cylinder or a hollow hoop?

The solid cylinder will always win due to lower rotational inertia.

What is torque and how is it calculated?

Torque (τ) is the rotational analogue of force, calculated as τ = F × Lever Arm.

What is centripetal force?

A real, center-seeking force acting perpendicular to an object's velocity vector, pulling it into a circular path.

What is centrifugal force?

An apparent, fictitious outward force caused by linear inertia, experienced in a rotating frame of reference.

What happens to an object when a string holding it snaps?

The object flies away in a straight line tangent to the circle, not radially outward.

What is the conservation of angular momentum?

If no external net torque acts on a system, total angular momentum remains constant: Iiωi = Ifωf.

What is Newton's Law of Universal Gravitation?

The gravitational force between two masses is Fg = G (m1m2 / d²), directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

How does distance affect gravitational force?

If distance is doubled, force drops to one-fourth; if tripled, to one-ninth; if halved, it quadruples.

What causes perceived weightlessness in free fall?

The absence of a support force against the body, not the absence of gravity.

What is the independence of projectile motion components?

Horizontal and vertical components operate independently; horizontal velocity remains constant while vertical motion is affected by gravity.

What is the maximum launch angle for horizontal range?

An angle of 45° provides the maximum horizontal range over flat terrain.

What defines a circular orbit?

Requires a horizontal speed of exactly 8 km/s, with constant orbital speed due to gravity acting perpendicular to the velocity vector.

What is the difference between circular and elliptical orbits?

Elliptical orbits occur when launch speed exceeds 8 km/s but is below escape velocity, resulting in variable speed.

What is frequency and how is it related to period?

Frequency (f) is the number of cycles per second; period (T) is the time for one cycle, with f = 1/T.

How is wave speed calculated?

Wave speed (v) is the product of frequency (f) and wavelength (λ): v = fλ.

What is the difference between transverse and longitudinal waves?

Transverse waves have medium particles vibrating perpendicular to wave propagation; longitudinal waves have particles vibrating parallel.

What are standing waves?

Waves featuring stationary nodes and antinodes due to continuous destructive and constructive interference.

What is the Doppler Effect?

An apparent shift in frequency due to motion; approaching sources yield higher frequency, receding sources yield lower frequency.

What type of wave is sound?

Sound is a mechanical longitudinal wave.

Why can't sound travel through a vacuum?

Sound requires a physical medium of atoms to pass vibrations along.

In which medium does sound travel fastest?

Sound travels fastest in rigid, highly elastic solids like steel.

How does temperature affect the speed of sound in air?

The speed of sound in air increases with temperature because warmer molecules collide more frequently.

What is resonance in the context of sound?

Resonance occurs when an external forced vibration matches an object's natural frequency, causing amplitude to grow dramatically.

What causes beats in sound?

Beats are periodic volume fluctuations caused by playing two slightly different frequencies simultaneously.

How is beat frequency calculated?

Beat frequency equals the absolute difference between two frequencies: fbeat = |f₁ - f₂|.

What is the principle of conservation of charge?

Net charge is always conserved; electrons are merely transferred.

What does Coulomb's Law describe?

Coulomb's Law describes the force between two charges and operates via an inverse-square law.

What is the difference between conductors and insulators?

Conductors have loose outer electrons free to drift, while insulators have tightly bound electrons locked to nuclei.

What is charge polarization?

Charge polarization is the realignment of surface charges in an insulator without physical charge transfer.

What is electric shielding?

Electric shielding is when excess charge on a metal conductor migrates to the outer surface, canceling the internal electric field.

What does Ohm's Law state?

Ohm's Law states that current (I) equals voltage (V) divided by resistance (R): I = V/R.

What happens in a series circuit?

In a series circuit, current is identical through all components, and total resistance adds up.

What happens in a parallel circuit?

In a parallel circuit, voltage is identical across all branches, and adding branches decreases total circuit resistance.

What is the significance of magnetic domains?

Magnetic domains are localized clusters of aligned atomic magnets; unmagnetized materials have randomly oriented domains.

What is Faraday's Law?

Faraday's Law states that a voltage is induced in a coil of wire whenever there is a change over time in the magnetic field lines passing through it.

What is the difference between motors and generators?

A motor converts electrical energy into mechanical spin, while a generator converts mechanical spin into electrical current.

What is the relationship between voltage and power in transformers?

In transformers, voltage scales with the coil loop ratio, but a transformer cannot step up energy or power.

What is the speed of light in a vacuum?

The speed of light in a vacuum is approximately 300,000 km/s.

What happens to light when it enters glass?

Light is absorbed and re-emitted by electrons in glass, slowing its average speed down to 0.67c.

What is the Law of Reflection?

The Law of Reflection states that the angle of incidence equals the angle of reflection.

What is total internal reflection?

Total internal reflection occurs when light moves from a slower to faster medium at an angle exceeding the critical angle.

What is the Principle of Equivalence in relativity?

The Principle of Equivalence states that the effects of a uniform gravitational field are indistinguishable from those of uniform linear acceleration.

What is gravitational time dilation?

Gravitational time dilation means that clocks tick slower in regions of stronger gravitational fields.

What causes gravitational redshift?

Gravitational redshift occurs when light climbing out of a strong gravitational well loses energy, decreasing its frequency.