USTET Abstract Reasoning — Mechanical ReasoningRevision Notes
Revision notes for USTET Abstract Reasoning Mechanical Reasoning — designed for time-pressed reviewers. These notes skip the basics and focus on what University of Santo Tomas consistently tests, so you spend your revision hours on the content most likely to appear on exam day.
Exam context
On the USTET 2026, the Abstract Reasoning subtest carries a "Core" weight in University of Santo Tomas's pattern. Mechanical Reasoning lands at position 4th out of 5 in the standard review order. Target score is Competitive overall score, and roughly a meaningful share of items come from Abstract Reasoning on a typical USTET paper.
Mechanical Reasoning - Revision notes
Mechanical Reasoning tests your ability to understand basic principles of mechanics, machinery, and motion without requiring specialized technical knowledge. This section appears in major Philippine entrance exams including UPCAT, ACET, and USTET. Success depends on logical reasoning about how simple machines, gears, levers, and fluid systems work in everyday situations.
Sections
Exam Tips
- Draw arrows to show direction of motion and force
- Use the inverse relationship principle: bigger = slower, smaller = faster
- Always check your answer by tracing the motion step by step
Key Points
- Focuses on reasoning ability, not memorized technical knowledge
- Questions present mechanical situations through pictures and diagrams
- Requires logical thinking about cause-and-effect relationships
- Tests understanding of basic physics principles in practical contexts
- Common topics include gears, pulleys, levers, fluid pressure, and motion
Definitions
Term
Mechanical Advantage
Definition
The ratio of output force to input force in a machine, showing how much the machine multiplies force
Importance
Helps determine efficiency and effectiveness of simple machines like levers and pulleys
Term
Gear Ratio
Definition
The relationship between the number of teeth or size of connected gears, determining relative speeds
Importance
Essential for solving gear-related problems in mechanical reasoning tests
Section Title
Understanding Mechanical Reasoning
Common Mistakes
- Assuming larger gears always turn faster (opposite is true)
- Forgetting that force and speed have inverse relationships
- Not considering the direction of rotation in gear systems
Formulas
Example
6cm gear drives 3cm gear: Speed Ratio = 6÷3 = 2:1 (small gear turns twice as fast)
Formula
Speed Ratio = Size of Driving Gear ÷ Size of Driven Gear
Variables
Driving Gear = input gear, Driven Gear = output gear
Application
Calculate how much faster or slower the driven gear turns
Exam Tips
- Always identify the input (driving) gear first
- For gear trains, work through each connection step by step
- Remember: big to small = speed up, small to big = slow down
Key Points
- Large gears drive small gears to turn faster
- Small gears drive large gears to turn slower but with more force
- Speed ratio is inversely proportional to size ratio
- In gear trains, multiply ratios to find final speed relationship
- Direction alternates with each gear connection (unless using belt drives)
Definitions
Term
Driving Gear
Definition
The gear that provides the input power and motion to the system
Importance
Starting point for calculating speed and force transmission through gear trains
Term
Driven Gear
Definition
The gear that receives power from the driving gear and produces the output motion
Importance
Final point where mechanical advantage or speed change is achieved
Section Title
Gears and Wheel Systems
Common Mistakes
- Confusing which gear is driving vs driven
- Forgetting to account for multiple gear connections in a train
- Mixing up speed and force relationships
Formulas
Example
Small 2cm wheel drives large 6cm wheel: RPM ratio = 6÷2 = 3:1 (large wheel turns 3× faster)
Formula
RPM Ratio = Diameter of Driven Wheel ÷ Diameter of Driving Wheel
Variables
RPM = Revolutions Per Minute, Diameter = wheel size
Application
Calculate relative speeds in belt drive systems
Exam Tips
- Belt drives keep the same rotation direction
- Focus on the wheel sizes to determine speed relationships
- The smallest driving wheel typically creates the highest output speed
Key Points
- Belt drives connect wheels of different sizes to transfer motion
- Unlike gears, belt drives maintain the same direction of rotation
- Smaller driving wheels paired with larger driven wheels increase speed
- The wheel with the highest RPM advantage determines fastest rotation
- Belt drives are commonly used in machines and engines
Definitions
Term
Belt Drive
Definition
A system using a flexible belt to transfer power between wheels or pulleys
Importance
Common mechanical system that maintains rotation direction while changing speed
Section Title
Belt Drive Systems
Common Mistakes
- Applying gear direction rules to belt drives
- Not recognizing that belt drives don't reverse direction
- Confusing belt drive speed ratios with gear ratios
Formulas
Example
Crowbar with 60cm effort arm and 10cm load arm: MA = 60÷10 = 6 (multiplies force by 6)
Formula
Mechanical Advantage = Effort Arm Length ÷ Load Arm Length
Variables
Effort Arm = distance from fulcrum to applied force, Load Arm = distance from fulcrum to load
Application
Calculate how much a lever multiplies input force
Exam Tips
- Always locate the fulcrum first
- Remember: longer effort arm = more mechanical advantage
- Draw a simple diagram to visualize the lever system
Key Points
- Levers multiply force or distance depending on fulcrum position
- Three classes of levers based on fulcrum, effort, and load positions
- Longer effort arm provides greater mechanical advantage
- Force and distance have inverse relationships in lever systems
- Common examples: scissors, pliers, crowbars, wheelbarrows
Definitions
Term
Fulcrum
Definition
The pivot point around which a lever rotates
Importance
Position determines the type of lever and mechanical advantage achieved
Term
First Class Lever
Definition
Fulcrum is between the effort and load (like a seesaw)
Importance
Can provide mechanical advantage for either force or distance depending on arm lengths
Section Title
Levers and Mechanical Advantage
Common Mistakes
- Confusing the three classes of levers
- Not identifying the fulcrum position correctly
- Assuming all levers provide mechanical advantage
Formulas
Example
100N force on 2m² piston: Pressure = 100÷2 = 50 Pa
Formula
Pressure = Force ÷ Area
Variables
Force = applied force in Newtons, Area = surface area in square meters
Application
Calculate pressure in hydraulic systems
Example
Small 1cm² piston drives large 10cm² piston: Force ratio = 10÷1 = 10:1
Formula
Hydraulic Force Ratio = Area of Output Piston ÷ Area of Input Piston
Variables
Output Piston = larger piston, Input Piston = smaller piston
Application
Calculate force multiplication in hydraulic systems
Exam Tips
- Remember: deeper = higher pressure
- In hydraulics, small input force can create large output force
- Always consider both force and area when solving pressure problems
Key Points
- Fluid pressure increases with depth due to weight of fluid above
- Pressure is equal at all points at the same horizontal level
- Hydraulic systems use fluid pressure to multiply force
- Smaller pistons create higher pressure, larger pistons provide more force
- Pascal's principle: pressure applied to confined fluid transmits equally in all directions
Definitions
Term
Hydraulic System
Definition
A system that uses confined liquid to transmit power and multiply force
Importance
Common in car brakes, jacks, and heavy machinery
Term
Pascal's Principle
Definition
Pressure applied to a confined fluid is transmitted equally in all directions
Importance
Fundamental principle explaining how hydraulic systems multiply force
Section Title
Fluid Pressure and Hydraulics
Common Mistakes
- Thinking pressure decreases with depth
- Not recognizing that hydraulic systems multiply force, not energy
- Confusing pressure with force in hydraulic calculations
Formulas
Example
Block-and-tackle with 4 rope segments supporting load: MA = 4 (reduces required force to 1/4)
Formula
Mechanical Advantage = Number of Rope Segments Supporting Load
Variables
Rope Segments = count of rope sections that directly support the moving load
Application
Calculate force reduction in pulley systems
Exam Tips
- Count only the rope segments directly supporting the moving load
- Fixed pulleys just redirect force, movable pulleys reduce force
- More pulleys = less force needed but more rope to pull
Key Points
- Fixed pulleys change direction of force but don't provide mechanical advantage
- Movable pulleys provide 2:1 mechanical advantage
- Multiple pulleys can be combined for greater mechanical advantage
- More rope segments supporting the load = greater mechanical advantage
- Trade-off between force reduction and distance increase
Definitions
Term
Fixed Pulley
Definition
A pulley attached to a fixed support that only changes the direction of applied force
Importance
Allows pulling downward to lift objects upward, but doesn't reduce required force
Term
Movable Pulley
Definition
A pulley that moves with the load, providing mechanical advantage
Importance
Reduces the force needed to lift loads by distributing weight across multiple rope segments
Section Title
Pulleys and Block-and-Tackle Systems
Common Mistakes
- Counting all rope segments instead of only those supporting the load
- Thinking fixed pulleys provide mechanical advantage
- Not recognizing the trade-off between force and distance
Connections
- Mechanical reasoning principles apply to Physics topics like simple machines and energy transfer
- Gear ratios and mechanical advantage connect to Mathematics ratio and proportion problems
- Hydraulic systems relate to fluid mechanics concepts in advanced Physics courses
- Lever principles appear in Biology when studying bone and muscle systems as biological levers
- These concepts have practical applications in engineering, automotive technology, and industrial design
Exam Strategy
For mechanical reasoning questions: (1) Identify the type of system (gears, levers, pulleys, hydraulics), (2) Locate the input and output components, (3) Apply the appropriate principle (inverse ratios for gears, mechanical advantage for levers), (4) Use logical reasoning rather than complex calculations, (5) Trace through the system step-by-step to verify your answer, (6) Remember that these questions test reasoning ability, not memorized formulas.
Quick Review Questions
If a 6cm gear drives a 3cm gear, how many times does the small gear turn for each turn of the large gear?
Speed ratio = 6÷3 = 2:1. The small gear turns twice as fast as the large gear.
In a lever system, where should the fulcrum be placed to get maximum mechanical advantage?
This maximizes the effort arm length while minimizing the load arm length, giving the highest mechanical advantage.
Why does water pressure increase as you go deeper in a swimming pool?
The deeper you go, the more water is above you, creating greater pressure due to the weight of that water column.
A pulley system has 4 rope segments supporting the load. What is the mechanical advantage?
Mechanical advantage equals the number of rope segments supporting the load. Each segment supports 1/4 of the total weight.
In a belt drive system, if a small wheel drives a large wheel, what happens to the speed?
Unlike gears, belt drives maintain the same direction but the larger wheel turns slower due to its greater circumference.
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