Chapters 1-3 R#1 Flashcards
1
Q
Chapter 1: Measurements
A
2
Q
What is mass?
A
mass is both a measure of matter and the property that resists changes in motion
3
Q
What are the SI units of mass?
A
Kilograms (Kg) and grams (g).
4
Q
What are the two main apparatus used to measure mass?
A
Beam balance and digital balance.
5
Q
What is the function of a beam balance?
A
To compare masses.
6
Q
What precaution should be taken when using a beam balance?
A
Place it on a horizontal (flat) surface.
7
Q
What is another name for a digital balance?
A
Sensitive balance, top-pan balance, or electronic balance.
8
Q
What are two precautions when using a digital balance?
A
- Place it on a horizontal surface
- Check for zero error.
9
Q
What is length?
A
The distance between two points.
10
Q
What are the SI units of length?
A
Meters (m), kilometers (Km), centimeters (cm), and millimeters (mm).
11
Q
What are three common apparatus used to measure length?
A
Meter ruler, measuring tape, micrometer.
12
Q
What is a meter ruler used for?
A
To measure up to 1 meter.
13
Q
What is a measuring tape used for?
A
To measure lengths greater than 1 meter.
14
Q
What is a micrometer used for?
A
To measure very small lengths (less than 1 cm), such as the thickness of wire or paper.
15
Q
How do you accurately measure the thickness of a sheet of paper?
A
- Check the zero reading of a micrometer.
- Measure the thickness of 20 sheets of paper.
- Divide the thickness recorded by 20.
- Repeat and take the average of results.
Extra:
* Use identical sheets of paper.
* Avoid parallax error by looking perpendicularly.
16
Q
How do you measure the length of a non-curved object?
A
Use a ruler: End length – Starting length.
17
Q
How do you measure the length of a curved object?
A
- Place the object between two wooden blocks or set squares.
- Use a ruler: End length – Starting length.
18
Q
How do you measure the inner diameter of a ring?
A
Calculate the total length of the ring using a ruler.
Subtract the inner thickness of both sides of the ring.
19
Q
What is time?
A
The measurement of the duration of an event.
20
Q
What are the SI units of time?
A
Seconds (s), minutes (min), hours (h) (convert all to seconds).
21
Q
What are two apparatus used to measure time?
A
Stopwatch and clock.
22
Q
How do you measure the period of a pendulum?
A
- Use a pendulum and stopwatch and a fiduciary aid to determine one complete cycle.
- Check the zero reading of the stopwatch.
- Start the stopwatch when releasing the pendulum.
- Count 20 oscillations and record the time.
- Divide the total time by 20 to get the period of one oscillation.
- Repeat and take the average.
23
Q
What are precautions in the pendulum experiment?
A
- Check for zero error.
- Don’t count too many oscillations to avoid loss of count.
24
Q
What are two sources of error in the pendulum experiment?
A
- Human error: reaction time.
- Instrument error: zero error, battery empty.
25
What is volume?
The space occupied by matter.
26
What are the SI units of volume?
Cubic centimeters (cm³), cubic millimeters (mm³), **cubic meters (m³).**
27
How do you convert volume units?
The same as length but raised to the power of 3
| cm³ to m³ (x 100^3)
28
What is the formula for the volume of a cube or cuboid?
L × W × H.
29
What is the formula for the volume of a cylinder?
πr²h.
30
What is the formula for the volume of a sphere?
4πr³/3.
31
How do you measure the volume of an irregular object?
Using the displacement method.
32
What apparatus are used in the displacement method?
Measuring cylinder, water, object, sinker (if needed).
33
Describe the steps of the displacement method.
* Add sufficient water to the measuring cylinder and record volume as V1.
* Submerge the object and record new volume as V2.
* Subtract V1 from V2 (V2 - V1) to get the volume of the object.
34
What are three precautions when using the displacement method?
* Avoid parallax error.
* Ensure the object is fully submerged.
* Use a sinker if the object is less dense than water.
35
What is density?
The mass per unit volume of a substance.
36
What is the formula for density?
Density = Mass / Volume (D = m/v).
37
What are the SI units of density?
**Kilograms per cubic meter (Kg/m³)** or grams per cubic centimeter (g/cm³).
38
How do you find the density of an object?
* Measure the mass using a digital balance.
* Measure the volume using the displacement method.
* Divide mass by volume (D = m/v).
39
Chapter 2: Speed, Velocity, and Acceleration
40
What is a scalar quantity?
A quantity that only has magnitude (size) only.
41
Give five examples of scalar quantities.
Mass, time, distance, volume, density, speed, energy and temperature.
42
What is a vector quantity?
A quantity that has both magnitude and direction.
43
Give examples of vector quantities.
Displacement, force, weight, velocity, acceleration, momentum, electric field strength and gravitational field strength.
44
What is the difference between distance and displacement?
* Distance: The total path traveled between two points, with no direction
* Displacement: the straight-line change in position from start to end, including direction
45
What is the formula for average speed?
Average speed = distance / time
46
How can you find average speed from a distance-time graph?
Use the gradient:
(𝑦2− 𝑦1) / (𝑥2 − 𝑥1)
(rise over run)
47
What is maximum speed?
The highest speed recorded, found by identifying the steepest straight line on a distance time graph.
48
What is instantaneous speed?
Speed at a specific moment in time.
49
How do you determine instantaneous velocity using a graph?
Instantaneous velocity is found by drawing a tangent at the point of interest on a velocity–time graph; the gradient of this tangent line represents the instantaneous velocity.
50
What is acceleration?
Acceleration is change in velocity per unit time
51
What is the formula for acceleration?
**a = (v−u) / t**
where:
* a = acceleration
* 𝑣 = final velocity
* 𝑢 = initial velocity
* 𝑡 = time
52
What is increasing acceleration? Give an example.
When speed increases at an increasing rate.
* Example: 1𝑚/𝑠, 3𝑚/𝑠, 7𝑚/𝑠 (+2,+4)
53
What is decreasing acceleration? Give an example.
When speed increases at a decreasing rate.
* Example: 1𝑚/𝑠, 5 𝑚/𝑠, 7 𝑚/𝑠 (+4, +2)
* Occurs in cars reaching terminal velocity.
54
What information can you extract from a velocity–time graph?
1. The gradient (slope) of a velocity–time graph gives the acceleration
2. The area under the curve represents the displacement of the object.
55
What is constant uniform acceleration? Give an example.
When speed increases at a constant rate.
* Example: 1𝑚/𝑠, 3 𝑚/𝑠, 5 𝑚/𝑠 (+2, +2).
56
What is constant deceleration? Give an example.
Velocity decreases at a constant rate.
* Example: 10 𝑚/𝑠, 7 𝑚/𝑠, 4 𝑚/𝑠 (−3, −3)
57
What is deceleration?
A deceleration is a negative acceleration. Negative change in velocity per unit time.
58
What does a straight, diagonal line on a distance-time graph mean?
Constant speed.
59
What does a curve on a distance-time graph mean?
Changing speed (acceleration or deceleration).
60
What does a horizontal line on a speed-time graph mean?
Constant velocity (speed stays the same over time).
61
How do you calculate distance from a speed-time graph?
Find the area under the graph.
62
What formula do you use for a triangle’s area?
1/2 × Base × Height
63
What formula do you use for a rectangle’s area?
Length × Width
64
What formula do you use for a trapezium’s area?
1/2 × (Base 1+ Base 2) × Height
65
How do you estimate the area under a curved speed-time graph?
* Find the midpoint of the curve.
* Divide the area into two shapes.
* Approximate each area and sum them.
66
What does a downward-sloping speed-time graph mean?
Deceleration (slowing down).
67
What happens when an acceleration-time graph is a horizontal line above zero?
Constant acceleration.
68
What is free-fall motion?
Motion under the effect of gravity only.
69
What is the acceleration due to gravity on Earth?
9.8𝑚/𝑠^2
70
What happens to speed and acceleration in free fall?
* Speed increases as the object falls.
* Acceleration remains constant at 9.8 𝑚/𝑠^2
71
Does mass affect free fall?
No, all objects fall at the same rate when air resistance is ignored.
72
Chapter 3F: Forces
73
What is a force?
A force is any push or pull on an object. It is a vector quantity.
74
What is a resultant force?
The total force acting on an object in a certain direction.
75
How do you calculate resultant force when forces are in the same direction?
Add them and keep the same direction.
76
How do you calculate resultant force when forces are in opposite directions?
Subtract the smaller force from the larger one and keep the direction of the larger force.
77
How do you calculate resultant force when forces are perpendicular?
Use the Pythagorean theorem:
𝐹 = Sqrt(𝐹(1)^2 +𝐹(2)^2)
78
How do you find the resultant force when forces act at an angle?
* If they have the same starting point → Use the Parallelogram Method.
* If they follow each other → Use the Triangle Method.
79
What is the formula for weight?
w = m × g
where:
* 𝑤 = weight
* 𝑚 = mass (kg)
* 𝑔 = acceleration due to gravity (9.8 𝑚/𝑠², use 10 𝑚/𝑠² in exams).
80
What is gravity (gravitational field strength)?
The force per unit mass. (A form of acceleration)
Changes based on planet (Earth: 9.8 m/s^2)
81
What is friction?
A force that opposes motion between solid surfaces.
82
What is air resistance?
A force that opposes motion in air. It increases with speed or larger surface area.
83
What is upthrust?
An upward force that occurs in liquids and gases.
84
What is tension?
A force that acts in strings, wires, and cables (e.g., a ceiling fan hanging from a wire).
85
What is normal force?
A contact force exerted by a solid surface perpendicular to an object.
86
What is Newton’s First Law of Motion?
If the resultant force is 0, **an object remains at rest or moves at constant velocity.**
87
What is Newton’s Second Law of Motion?
The resultant force acting on an object is equal to mass × acceleration:
* 𝐹 = 𝑚 x 𝑎
88
What is the relationship between force, mass, and acceleration?
* Force (F) is directly proportional to mass (m).
* Force (F) is directly proportional to acceleration (a).
* Mass (m) is inversely proportional to acceleration (a).
89
What is Newton’s Third Law of Motion?
For every action, there is an equal and opposite reaction.
90
What happens immediately after a skydiver jumps?
He falls under the effect of his weight only → Acceleration is constant, speed increases.
91
What happens as the skydiver falls at the start?
His speed increases, so air resistance increases → Acceleration and resultant force decrease.
* Resultant force = weight − air resistance
92
What happens when the skydiver reaches terminal velocity?
Air resistance = weight → Resultant force = 0 → Speed becomes constant. (Newton’s first Law)
93
What happens when the parachute opens?
Surface area increases, so air resistance > weight → The skydiver decelerates.
* Resultant force = air resistance − weight
94
What happens when the skydiver reaches terminal velocity again?
His speed decreases, so air resistance decreases until it equals weight → He falls at a safe constant speed.
95
What is circular motion?
Motion where an object moves at constant speed but is always accelerating because its direction changes due to a centripetal force.
96
What is the force that keeps an object moving in a circle?
Centripetal force.
97
In which direction does centripetal force act?
Toward the center of the circular path, perpendicular to the object’s motion.
98
What causes circular motion?
Friction between the object and the surface (e.g., car tires on a road).
99
Chapter 3P: Pressure
100
What is pressure in solids?
Pressure is the force that acts on an area.
101
What is the formula for pressure in solids?
𝑃 = 𝐹/𝐴
(Pressure = Force / Area).
102
What are the units of pressure in solids?
N/cm², N/m², or **Pascals (Pa), where 1 Pa = 1 N/m².**
103
What is pressure in liquids?
Pressure in liquids is the force exerted on the surrounding container.
104
What is the formula for pressure in liquids?
P = ρgh
(Pressure = Density × Gravity × Height).
105
What unit is used for liquid pressure?
Pascals (Pa), **ensuring all values are in meters.**
106
What is atmospheric pressure?
The pressure exerted by the air around us.
107
How do you calculate total pressure in a liquid?
Total Pressure = Atmospheric Pressure + Pressure due to Liquid.
108
What does it mean that fluid pressure is isotropic?
It means that pressure in a fluid is exerted equally in all directions—a principle known as Pascal's Principle.
109
Chapter 3M: Moment
110
What is a moment?
The turning effect of a force about a pivot.
Formula:
* **Moment = Force × Perpendicular Distance from Pivot**
111
What happens if a force acts on the pivot?
The perpendicular distance d = 0, so the moment = 0.
112
What happens if the total moment clockwise is greater than the total moment anticlockwise?
The object will turn clockwise.
113
What happens if the total moment clockwise is less than the total moment anticlockwise?
The object will turn anticlockwise.
114
What happens if the total moment clockwise equals the total moment anticlockwise?
The object is balanced and in equilibrium.
115
What are the two conditions for an object to be in equilibrium?
No resultant force acts on the object:
* Force up = Force down
* Force right = Force left
No resultant moment acts on the object:
* Total Moment Clockwise = Total Moment Anticlockwise
116
What are the steps to solve a moment problem?
1. Calculate the moment caused by all given forces.
2. Determine which forces are clockwise and which are anticlockwise.
3. Use Total Moment Clockwise = Total Moment Anticlockwise to solve for missing forces or distances.
117
How do you calculate the force acting on a pivot?
Use the rule Force up = Force down (since the force direction is downward).
118
What is the center of mass?
The point at which the weight of an object acts.
119
How can you find the center of mass practically?
Move the object over a pivot until it balances. That point is the center of mass.
120
How can you find the center of mass for regular shapes?
The center of mass is located at the center of the 2D or 3D shape.
121
How can you find the center of mass for irregular shapes?
1. Hang the object from a pin at any point.
2. Use a plumbline to draw a line of weight.
3. Repeat from at least three different points.
4. The point of intersection of the lines is the center of mass.
122
Where is the center of mass in irregular objects with uneven weight?
It is shifted towards the heavier parts.
123
What factors increase the stability of an object?
* Lower center of mass (closer to the ground).
* Larger base area.
* The line of weight must be within the base area of the object.
| Explain by: “center of mass doesn’t/does fall outside its base area”
124
What is the SI unit for moment, and how is moment defined?
The SI unit for moment is the Newton-meter (N·m). Moment is defined as the force multiplied by the perpendicular distance from the pivot.
125
Chapter 3H: Hooke's Law
126
What is Hooke’s Law?
Extension is directly proportional to load.
127
What is L₁?
The original unstretched length of an object.
128
What is L₂?
The stretched length of an object when a load is added.
129
How do you calculate extension?
Extension = L₂ - L₁
130
What are the three key features of a graph that follows Hooke’s Law?
* Straight line
* Passes through the origin
* As force increases, extension increases
131
What is the formula for Hooke’s Law?
Force = K × Extension (F = KX)
132
What is K in Hooke’s Law?
The spring constant (stiffness of the spring).
133
How do you calculate the spring constant (K)?
K = F/X (Use any values from the straight part of the graph).
134
What is the limit of proportionality?
The maximum load where a spring still obeys Hooke’s Law.
135
What happens when the limit of proportionality is exceeded?
The graph bends towards the extension axis and the object no longer obeys Hooke’s Law (Load is no longer directly proportional to extension)
136
Are extension/force and length/force graphs the same?
No, we must account for the difference between L₁ and L₂ when dealing with a length/force graph
137
What are the units of the spring constant
𝑘 in Hooke’s Law?
The spring constant
𝑘 is measured in Newtons per meter (N/m).
