TUTORIAL UTS FISIKA DASAR TPB ITERA 2025 PART 1

Main ideas & lessons conveyed (Part 1: Basic Physics TPB/ITERA UTS Tutorial)

Course/session goal

• The instructor reiterates that the previous link may be wrong, so the session is re-uploaded and students can check it on YouTube (and optionally join on Zoom).
• Tonight’s focus:
  • Basic physics exam-style questions
  • A review of the core syllabus that will likely appear in UTS, with similar question types across Monday/Tuesday sessions.

Roadmap of the covered material (6 “meetings” summarized)

1. Vector quantities + measurements
2. Quantities and units, including basic and derived quantities
3. Kinematics
4. Dynamics
5. Work & Energy
6. Impulse & Momentum
   • Later mentioned: Waves and Thermodynamics

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Detailed methodology: Dimensional analysis (core teaching)

1) Rule for determining formulas from dimensions

• Key rule: For a proposed relationship, the dimension of the left-hand side must equal the dimension of the right-hand side.
• If unknown exponents are involved, solve by matching powers of:
  • Length (L)
  • Mass (M)
  • Time (T)

2) Basic vs derived quantities (units & dimensions)

• Basic (principal) quantities in SI:
  • Mass: unit kilogram (kg), dimension M
  • Length: unit meter (m), dimension L
  • Time: unit second (s), dimension T
• Derived quantities depend on combinations of basics.
  • Example: Speed
    • ( v = \frac{\text{distance}}{\text{time}} )
    • dimension: ( [v] = L T^{-1} )

3) Example methodology: Solve unknown exponents using dimensions

• Given an assumed form like:
  • ( x = g^\alpha t^\beta )
• Steps:
  1. Identify dimensions:
     • ( [x] = L )
     • ( [g] = L T^{-2} ) (gravity as acceleration)
     • ( [t] = T )
  2. Substitute dimensional forms:
     • ( L = (L T^{-2})^\alpha (T)^\beta )
  3. Expand and match exponents:
     • match L powers and T powers separately
  4. Solve for ( \alpha ) and ( \beta )
• Instructor emphasis:
  • the dimensional equation must be consistent
  • if exponents contradict, the formula likely needs an additional constant (a dimensional constant)

4) Handling inconsistency (why constants may be required)

• If a proposed relation like ( F(\rho, v) ) yields contradictory exponent equations:
  • conclude the model is missing information
  • add a constant with appropriate dimensions (e.g., ( C ) or ( k )) to restore consistency
• This idea appears in discussions of:
  • force as a function of density and velocity
  • later correction that drag-force modeling often includes area/geometry via a dimensional constant

5) Drag force example (dimensional-analysis style outcome)

• Instructor models drag force as:
  • ( F = C \rho^x v^y A^z )
• Uses:
  • ( [\rho] = M L^{-3} )
  • ( [v] = L T^{-1} )
  • ( [A] = L^2 )
  • ( [F] = M L T^{-2} )
• Matching exponents yields a consistent set.
• Final conceptual takeaway (as stated):
  • drag-like dependence involves terms proportional to:
    • density
    • velocity squared
    • area
  • common form:
    • ( F \approx \frac{1}{2} c\, \rho \, v^2 \, A ) (with a coefficient)

6) Dimensional analysis for kinematic relations (example with speed)

• Demonstrates:
  • ( v = \frac{x}{t} \Rightarrow [v] = L T^{-1} )
• Then shows how to match dimensions when exponents are unknown, e.g.:
  • ( x = v^a t^b )
  • match L and T exponents to get ( a ) and ( b )
• Example outcome for familiar kinematics (constant speed):
  • ( x = v t )

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Detailed conceptual explanation: Vectors & vector displacement

1) What makes a vector different

• Vectors have:
  • Magnitude
  • Direction
• Example:
  • Velocity is a vector
  • Speed is a scalar (distance/time without direction)

2) Displacement vs distance (important distinction)

• Distance traveled: scalar, always accumulates positively.
• Displacement: vector, depends on start-to-end direction.
• Example:
  • Move from A to B and then return B to A:
    • Displacement can become 0
    • Distance traveled is nonzero

3) 2D coordinate/vector notation

• Unit vectors:
  • East (positive x) → ( \hat{i} )
  • North (positive y) → ( \hat{j} )
  • Opposite directions are negative:
    • West → ( -\hat{i} )
    • South → ( -\hat{j} )
• Combined motion (e.g., 3 m east then 4 m north):
  • displacement vector: ( \Delta \vec{s} = 3\hat{i} + 4\hat{j} )
  • magnitude:
    • ( |\Delta \vec{s}| = \sqrt{3^2 + 4^2} = 5\,\text{m} )

4) Magnitude formula via Pythagorean theorem / dot-product intuition

• For ( \vec{A} = a\hat{i} + b\hat{j} ):
  • ( |\vec{A}| = \sqrt{a^2 + b^2} )
• Brief connection:
  • unit vectors are perpendicular, so cross terms drop (cos 90° = 0)

5) Step-by-step guidance for displacement problems

• Convert each leg into signed components:
  • East = ( + ) in ( \hat{i} )
  • West = ( - ) in ( \hat{i} )
  • North = ( + ) in ( \hat{j} )
  • South = ( - ) in ( \hat{j} )
• Add/subtract components:
  • ( \Delta \vec{s} = \left(\sum x\right)\hat{i} + \left(\sum y\right)\hat{j} )
• Compute magnitude:
  • ( |\Delta \vec{s}| = \sqrt{\left(\sum x\right)^2 + \left(\sum y\right)^2} )

6) More than 2 axes (3D mention)

• In 3D:
  • include ( \hat{k} )
  • magnitude:
    • ( |\vec{r}| = \sqrt{x^2 + y^2 + z^2} )
• Instructor notes exams emphasize 2D illustrations here.

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Kinematics overview (motion without focusing on causes)

1) Definitions

• Kinematics studies motion/trajectory vs time, without analyzing forces.

2) Constant speed vs changing speed

• Constant speed:
  • displacement–position behavior is described with straight-line graph behavior.
• Accelerated motion:
  • ( x = x_0 + v_0 t + \frac{1}{2} a t^2 )

3) Free fall key idea (gravity only)

• Assumptions in the example:
  • initial velocity often taken as 0
  • acceleration = g
• Vertical motion:
  • ( h = \frac{1}{2} g t^2 )
  • implies scaling:
    • ( t \propto \sqrt{h} )
• If height doubles, time increases by ( \sqrt{2} ), etc. (explained verbally)

4) Interpreting symbols

• Clarification:
  • final velocity means the velocity at the point of interest (e.g., at the ground/contact point)

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Dynamics overview (causes of motion)

1) Newton’s 3 laws (as stated/used)

1. Inertia / net force zero:
   • If ( \sum F = 0 ), velocity stays constant (including possibly ( v=0 )).
2. Acceleration from net force:
   • ( \sum F = m a )
   • larger force → larger acceleration (proportional)
3. Action–reaction pairs:
   • forces occur in equal magnitude and opposite direction between interacting bodies

2) Worked conceptual examples of forces

• Object at rest on a table:
  • weight downward (gravity)
  • normal force upward
  • static friction prevents slipping
• Object on an inclined plane with possible friction:
  • components of weight:
    • parallel: ( mg\sin\theta )
    • perpendicular: ( mg\cos\theta )
  • friction depends on normal force:
    • ( f_k = \mu_k N )

3) Special angle case reasoning

• If friction coefficient is 0 (slippery plane):
  • acceleration comes purely from the gravity component along the incline:
    • ( a = g\sin\theta )
• Free fall corresponds to a special geometry where the component becomes effectively ( g ) (per instructor angle-based explanation)

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Work & Energy overview (conservation of mechanical energy)

Key concept

• Conservation of mechanical energy:
  • total mechanical energy at one point = total mechanical energy at another point
• mechanical energy = potential energy + kinetic energy

Inclined-plane example structure (as explained)

• Starting at height ( H ) and released:
  • initial: ( m g H + \frac{1}{2} m v^2 ) (often with ( v=0 ) in the example)
• final at a lower point:
  • use energy equality to solve for speed without requiring a friction-acceleration step (when appropriate)

Practical advice from instructor

• Sometimes easier to use energy conservation rather than kinematics/dynamics when problems focus on heights.

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Closing exam logistics & scope

UTS format described

• multiple-choice + fill-in/short-answer done on a computer
• paper used for some parts later
• around 10 questions (as explained)
• Monday and Tuesday sessions differ but questions are similar in topics

Confirmed scope emphasis

• Focus on “basic physics” topics:
  • quantities/units, vectors, kinematics, dynamics, work-energy, etc.
• Modern physics constants (example: Planck constant) are not part of this specific exam segment.

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Speakers / sources featured

• Main speaker/instructor (unnamed in subtitles): leads the “Tutorial UTS FISIKA DASAR TPB ITERA 2025 PART 1” explanations.
• Students/participants (unnamed): ask questions via Zoom/YouTube chat.
• “Mr. Yoga” (mentioned): referenced when describing that intro materials may differ under another instructor/program coordinator.