CAPE Physics Unit 1 - Study Questions Flashcards
(78 cards)
1
Q
What is the difference between scalar and vector quantities?
A
Scalars have magnitude only (e.g., mass, speed, time), while vectors have magnitude and direction (e.g., velocity, force, acceleration).
2
Q
Derive the equations of motion for constant acceleration.
A
v = u + at
s = ut + 1/2 at²
v² = u² + 2as
Where:
u = initial velocity
v = final velocity
a = acceleration
s = displacement
t = time
3
Q
What is the significance of the area under a velocity-time graph?
A
It gives the displacement of the object.
4
Q
A car accelerates from rest at 2.5 m/s² for 8 seconds. Calculate its final velocity.
A
Final velocity: v = 2.5 x 8 = 20 m/s
5
Q
A car accelerates from rest at 2.5 m/s² for 8 seconds. Calculate the distance covered.
A
Distance: s = 0.5 x 2.5 x 8² = 80 m
6
Q
State Newton’s three laws of motion.
A
- An object remains at rest or in uniform motion unless acted upon.
- F=ma: acceleration is proportional to net force.
- If body A exerts a force on body B, then B exerts an equal and oppositely directed force on A.
7
Q
How does mass differ from weight?
A
Mass is the amount of matter (scalar, constant), while weight is the force due to gravity (vector, varies with location).
8
Q
A 10 kg object is pulled with a force of 50 N. If friction is 20 N, find acceleration.
A
Net force = 50 N – 20 N = 30 N
a = F/m = 30 N / 10 kg = 3 m/s²
9
Q
Define work, energy, and power.
A
- Work: Force × displacement in the direction of force.
- Energy: Capacity to do work.
- Power: Rate of doing work or energy transfer.
10
Q
What is the work-energy principle?
A
The work done by a net force is equal to the change in kinetic energy.
11
Q
A machine does 1000 J in 20 s. What is its power output?
A
P = 1000 J / 20 s = 50 W
12
Q
What provides the centripetal force in circular motion?
A
The centripetal force is provided by tension, gravity, or friction depending on the context.
13
Q
Derive the expression for centripetal acceleration.
A
a = v²/r, where v is speed and r is radius.
14
Q
Compare gravitational field strength and gravitational potential.
A
- Field strength: Force per unit mass (N/kg).
- Potential: Work done per unit mass to move a mass from infinity (J/kg).
15
Q
What are the assumptions of the kinetic theory of gases?
A
- Molecules move randomly.
- Have elastic collisions.
- Occupy negligible volume.
- Experience negligible intermolecular forces.
16
Q
Difference between heat capacity and specific heat capacity?
A
- Heat capacity: Heat to raise an object’s temperature by 1°C.
- Specific heat capacity: Heat to raise 1 kg of a substance by 1°C.
17
Q
How is temperature measured on Celsius and Kelvin scales?
A
T(K) = T(°C) + 273.15
18
Q
State and explain the first law of thermodynamics.
A
ΔQ = ΔU + W: Heat added = increase in internal energy + work done.
19
Q
Describe an isothermal and an adiabatic process.
A
- Isothermal: Constant temperature, no change in internal energy.
- Adiabatic: No heat exchange, energy change only affects internal energy.
20
Q
A gas expands adiabatically. What happens to temperature and why?
A
Temperature decreases because internal energy is used to do work.
21
Q
Differentiate between transverse and longitudinal waves.
A
- Transverse: Particles move perpendicular to wave direction (e.g., light).
- Longitudinal: Particles move parallel to wave direction (e.g., sound).
22
Q
What are phase, frequency, and wavelength?
A
- Phase: Fraction of a cycle completed.
- Frequency: Number of cycles per second (Hz).
- Wavelength: Distance between two successive in-phase points.
23
Q
Describe the principle of superposition.
A
The resultant displacement is the sum of the individual displacements of overlapping waves.
24
Q
Define SHM and give the conditions for it.
A
SHM occurs when the restoring force is proportional and opposite to displacement: a = -ω²x
25
Derive the period of a simple pendulum.
T = 2π√(l/g)
26
What is resonance and how can it be dangerous?
Resonance occurs when the driving frequency matches the natural frequency, leading to large amplitude vibrations (e.g., collapse of bridges).
27
How does the speed of sound change in different media?
Sound travels fastest in solids, slower in liquids, and slowest in gases.
28
Explain diffraction and interference.
* Diffraction: Spreading of waves when passing through an opening or around obstacles.
* Interference: Superposition of waves causing constructive or destructive patterns.
29
What is the Doppler effect?
It is the change in observed frequency due to relative motion between a wave source and an observer.
30
31
What is Simple Harmonic Motion?
SHM is motion where the restoring force is proportional to and directed towards the displacement from equilibrium:
a = -⍵²x
## Footnote
This definition highlights the relationship between restoring force and displacement.
32
What is the general equation for displacement in SHM?
x(t) = x₀ cos(ωt) or x(t) = x₀ sin(ωt)
## Footnote
This equation describes how displacement varies over time in SHM.
33
How is angular frequency ? related to period and frequency?
ω = 2πf = 2π/T
## Footnote
This relationship shows how angular frequency connects with both frequency and period.
34
How do kinetic and potential energy vary in SHM?
At max displacement: PE max, KE zero. At equilibrium: KE max, PE zero. Total energy is constant.
## Footnote
This describes the energy transformations within SHM.
35
Give two examples of systems that undergo SHM.
Simple pendulum (small angle), mass-spring system.
## Footnote
These are classic examples of systems exhibiting SHM.
36
What are the conditions for SHM in a pendulum?
Small angle approximation (<10°), restoring force must be proportional to displacement.
## Footnote
These conditions ensure that the motion can be approximated as SHM.
37
Show how a vertical mass-spring system undergoes SHM.
F = −kx
= ma⇒a
=−mkx
So it is SHM.
## Footnote
This derivation illustrates the fundamental principles of SHM in a mass-spring system.
38
What does the displacement vs. time graph of SHM look like?
A sine or cosine wave.
## Footnote
This graph visually represents the periodic nature of SHM.
39
At what displacement is the acceleration maximum?
At maximum displacement (amplitude).
## Footnote
This indicates that acceleration is greatest when the object is furthest from equilibrium.
40
What is damping in SHM?
Loss of energy over time due to friction/resistance, causing amplitude to decrease.
## Footnote
Damping affects the longevity of oscillations in SHM.
41
Define resonance.
When driving frequency equals natural frequency, amplitude is maximum.
## Footnote
Resonance can lead to significant increases in oscillation amplitude.
42
What is the sharpness of resonance affected by?
By the amount of damping.
## Footnote
More damping results in a broader resonance peak, while less damping leads to a sharper peak.
43
What is internal energy?
The total energy contained in a system due to the kinetic and potential energy of its particles.
## Footnote
Internal energy is a state function and is crucial for understanding thermodynamic processes.
44
How does internal energy change during a phase change?
It increases or decreases, but temperature remains constant during the phase change.
## Footnote
This is due to energy being used to break intermolecular bonds rather than increasing temperature.
45
State the First Law of Thermodynamics.
ΔU=Q−W,
where ΔU = change in internal energy, Q = heat added, and W = work done by the system.
## Footnote
This law reflects the conservation of energy principle in thermodynamic processes.
46
If 500 J of heat is added to a gas, and it does 200 J of work, what is the change in internal energy?
ΔU = 500 J - 200 J = 300 J.
## Footnote
This calculation illustrates the application of the First Law of Thermodynamics.
47
What are the assumptions of the kinetic theory of gases?
Random motion, elastic collisions, negligible intermolecular forces, negligible molecular volume.
## Footnote
These assumptions help explain the behavior of ideal gases.
48
Write the ideal gas equation.
PV = nRT.
## Footnote
This equation relates pressure (P), volume (V), amount of gas (n), the ideal gas constant (R), and temperature (T).
49
What is the relationship between pressure and mean squared speed?
P=1/3ρs²
Where ρ is the gas density and s² is the mean square speed.
## Footnote
This relationship arises from the kinetic theory of gases and shows how molecular motion contributes to pressure.
50
What is the difference between specific heat capacity and heat capacity?
Specific: energy to raise 1 kg by 1°C. Heat capacity: energy to raise the object by 1°C.
## Footnote
Specific heat capacity is mass-dependent, while heat capacity is not.
51
What is the molar heat capacity at constant volume for a monoatomic gas?
CV = (3/2)R.
## Footnote
This value is derived from the kinetic theory and applies to ideal monoatomic gases.
52
How is work done by a gas during expansion calculated from a P-V graph?
By finding the area under the curve on the pressure-volume graph.
## Footnote
This method visually represents the work done during gas expansion or compression.
53
State Newton's Law of Universal Gravitation.
F = Gm₁m₂ / r²
## Footnote
G is the gravitational constant, m₁ and m₂ are the masses, and r is the distance between their centers.
54
What is a gravitational field?
A region around a mass where another mass experiences a gravitational force.
55
Define gravitational field strength.
g = F/m = GM/r²
## Footnote
F is the gravitational force, m is the mass experiencing the force, G is the gravitational constant, M is the mass creating the field, and r is the distance from the center of mass.
56
What is gravitational potential?
Work done per unit mass to bring a test mass from infinity to a point:
V = -GM/r.
57
Is gravitational potential a vector or scalar?
Scalar. It is always negative.
58
What is a geostationary satellite?
A satellite orbiting with a 24h period above the equator, appearing stationary.
59
State Kepler's 3rd Law.
T² ∝ r³
## Footnote
T is the orbital period and r is the average distance from the sun.
60
What is the difference between gravitational field strength and potential?
g is force per unit mass (vector), V is energy per unit mass (scalar).
61
Why is gravity stronger at the poles than the equator?
The Earth is a geoid, so poles are closer to the center.
62
What is an equipotential line?
A line where all points have the same gravitational potential; no work is done moving along it.
63
What is the difference between transverse and longitudinal waves?
Transverse: Particles vibrate perpendicular to wave direction (e.g., light, water). Longitudinal: Particles vibrate parallel to wave direction (e.g., sound).
64
Can longitudinal waves be polarized?
No, only transverse waves can be polarized.
65
Define wavelength, frequency, and amplitude.
Wavelength (?): Distance between two points in phase. Frequency (f): Number of waves per second. Amplitude (A): Maximum displacement from equilibrium.
66
What is the wave speed equation?
v = fλ, where v is wave speed, f is frequency, and λ is wavelength.
67
What is reflection and what rule does it follow?
When a wave bounces off a surface. It obeys: Angle of incidence = Angle of reflection.
68
What causes refraction?
Change in speed due to a change in medium density, causing wave to bend. Wavelength changes; frequency stays constant.
69
When does diffraction become noticeable?
When the gap size is approximately equal to the wavelength.
70
What is constructive and destructive interference?
Constructive: Crest meets crest (amplitudes add). Destructive: Crest meets trough (amplitudes cancel).
71
What condition must waves meet to form a stable interference pattern?
Waves must be coherent and have equal/similar amplitude.
72
What causes a stationary wave?
Two identical, coherent waves traveling in opposite directions interfere, forming nodes and antinodes.
73
How far apart are nodes in a stationary wave?
Half a wavelength (λ/2).
74
What pattern is seen in Young's double slit experiment?
An evenly spaced fringe pattern of bright and dark bands due to interference.
75
What is the equation for fringe separation?
x = λD/a, where x = fringe spacing, λ = wavelength, D = distance to screen, a = slit separation.
76
How does a diffraction grating work?
Multiple slits produce constructive interference at angles where: dsinθ = nλ.
77
List the EM spectrum in order of decreasing wavelength.
Radio, microwaves, infrared, visible, UV, X-rays, gamma.
78
What do all electromagnetic waves have in common?
They are transverse, travel at light speed, and can be reflected, refracted, diffracted, and polarized.
