Force, Pressure and Energy
Types of Force, Pressure, Atmospheric Pressure, Types of Energy, Work, Power - TNPSC Science guide.
Learning Content
๐ช Force - Introduction!
Force = Factor that changes the position of an object
Unit:Newton (N)| CGS:dyne
๐ Key types - MASTER TABLE
| Type of key | English | Explanation | example |
|---|---|---|---|
| Gravity | Gravitational Force | The force that the earth pulls on objects | ๐ Falling Apples |
| Frictional force | Frictional Force | A force resisting motion | ๐ Braking |
| Muscle force | Muscular Force | Force exerted by muscles | ๐ช Weight lifting |
| Magnetic force | Magnetic Force | Magnetic force of attraction/repulsion | ๐งฒ Magnet attracts iron |
| Electrical force | Electric Force | Force between charges | โก Level electricity |
๐ Newton Laws - Newton Laws
| fate | Name | Explanation | formula |
|---|---|---|---|
| Rule I | Law of Inertia | If there is no force then the position will not change | - |
| Rule II | Law of force | Force = Mass × Acceleration | F = ma |
| Rule III | Verb-reaction | Every reaction has a reaction | Fโ = -Fโ |
๐ฏ Key - Key Formulas
๐ Basic Formulas:
- Force F = ma
- Weight W = mg(g = 9.8 m/s²)
- Momentum p = mv
- 1 N = 10โต dyne
๐ก Memory Tips:
- F =Force =mass ×aacceleration
- Mass doesn't change, weight does!
- Weight on Moon = 1/6 on Earth
๐ Friction force - Friction
| Type | Explanation |
|---|---|
| Level friction | While in the material state |
| Slip friction | When the object slips |
| Rolling friction | When the object is rolling (very low) |
๐ฏRolling Friction < Sliding Friction < Static Friction
โฌ๏ธ Pressure (Pressure) - Introduction!
Pressure = Force / Area
Unit:Pascal (Pa)= N/m²
๐ Stress Types - MASTER TABLE
| Pressure type | English | formula | example |
|---|---|---|---|
| solid pressure | Solid Pressure | P = F/A | ๐ Nail piercing |
| Fluid pressure | Liquid Pressure | P = hρg | ๐ Water pressure |
| torsional pressure | Atmospheric Pressure | 76 cm Hg | ๐ฌ๏ธ Air pressure |
๐ Important rules - Laws
| fate | who discovered | Explanation | application |
|---|---|---|---|
| Pascal's law | Blaise Pascal | Pressure is evenly distributed in the fluid | Hydraulic brake, lift |
| Archimedes' Law | Archimedes | A submerged object is pushed upward | Floating the ship |
| Bernoulli's law | Daniel Bernoulli | More speed = less pressure | Airplane flying |
๐ฏ Pressure - Comparison of Units
| unit | value | application |
|---|---|---|
| 1 atm | 101325 Pa | Atmospheric pressure |
| 1 bar | 10โต Pa | Weather report |
| 76 cm Hg | 1 atm | Mercury manometer |
| 1 torr | 1 mm Hg | Vacuum gauge |
๐ก Stress - Reminder Tips
๐ด Less area = more pressure:
- ๐ Nail tip sharpness
- ๐ช Knife Sharpness
- ๐ Damage to high heels
๐ข More surface area = less pressure:
- ๐ช Camel is broad footed
- ๐ฟ Skiing board
- ๐๏ธ Building foundation
๐ฏP = F/A→ more area (A) = less pressure (P)!
โก Energy (Energy) - Introduction!
Energy = capacity to do work
Unit:Joule (J)| CGS:erg
๐ Energy Types - MASTER TABLE
| Type of energy | English | formula | example |
|---|---|---|---|
| kinetic energy | Kinetic Energy | KE = ½mv² | ๐ Running car |
| level energy | Potential Energy | PE = mgh | ๐ฆ Meaning at height |
| Heat energy | Heat Energy | Q = mcΔT | ๐ฅ Fire |
| Light energy | Light Energy | E = hν | ๐ก Lamp |
| Electrical energy | Electrical Energy | E = VIt | โก Electricity |
| Sound energy | Sound Energy | - | ๐ Speaker |
| Atomic energy | Nuclear Energy | E = mc² | โข๏ธ Nuclear power plant |
๐ Energy Conversions - Energy Conversions
| device | input | โ | publication |
|---|---|---|---|
| ๐ก Electric light | Electrical energy | โ | Light + Heat |
| ๐ Battery | Chemical energy | โ | Electrical energy |
| โ๏ธ Solar cell | Light energy | โ | Electrical energy |
| ๐ค Microphone | Sound energy | โ | Electrical energy |
| ๐ Speaker | Electrical energy | โ | Sound energy |
| โ๏ธ Motor | Electrical energy | โ | kinetic energy |
| ๐ Generator | kinetic energy | โ | Electrical energy |
๐ฏ Energy Units - Comparison
| 1 J | = 10โท erg |
| 1 kWh | = 3.6 × 10โถ J (1 unit) |
| 1 eV | = 1.6 × 10โป¹โน J |
| 1 cal | = 4.186 J |
๐ฏEnergy does not perish, form changes!- Law of Invariance of Energy
๐ง Work & Power - Work & Power!
๐ Work vs Energy vs Efficiency - Comparison
| measurement | definition | formula | SI unit | CGS unit |
|---|---|---|---|---|
| Work | Force × Displacement | W = F × d | Joule (J) | Erk |
| Energy | Ability to work | KE, PE | Joule (J) | Erk |
| Power | Work / Time | P = W/t | Watt (W) | erg/sec |
โก Capacity units - Power Units
| 1 W | = 1 J/s |
| 1 kW | = 1000 W |
| 1 HP (Horse Power) | =746 W |
| 1 MW | = 10โถ W |
๐ฏ1 HP = 746 W- TNPSC Frequently Asked Question!
๐ด When job = 0?
1๏ธโฃ force = 0
Without the key, there is no work
2๏ธโฃ Displacement = 0
Pushing the wall (not moving)
3๏ธโฃ θ = 90°
Force ⊥ Displacement (wage)
๐กWalking with a load on the head- Force is upward, movement is sideways → W = 0!
๐ฏ Simple Machines - Simple Machines
| machine | example | benefit |
|---|---|---|
| Lever | Scissors, log breaker | Force amplification |
| Pulley | Well pulley | Change of direction |
| ramp | Ladder, skateboard | Low key |
| wedge | Ax, nail | Splitting |
| screw | Screw, Jack | Force amplification |
๐ TNPSC Main Questions & Shortcuts!
๐ฏ TNPSC Frequently Asked Questions
| Q: SI unit of force? | โ Newton (N) |
| Q: SI unit of pressure? | โ Pascal (Pa) |
| Q: SI unit of energy? | โ Joule (J) |
| Q: SI unit of capacity? | โ Watt (W) |
| Q: 1 horsepower = ? | โ 746 watts |
| Q: E = mc² - whose formula? | โ Einstein |
| Q: Pascal's Law - Application? | โ Hydraulic brake, lift |
| Q: Archimedes Rule - Application? | โ Boating, swimming |
| Q: Flying a plane - which rule? | โ Bernoulli's law |
| Q: Weight on the moon? | โ 1/6 times that on Earth |
๐ก SUPER SHORTCUT - formula recall!
๐ต "FMA" - key
F = ma
Force = Mass × Acceleration
๐ข "WFD" - Work
W = Fd
Work = Force × Distance
๐ก "PWT" - Capacity
P = W/t
Power = Work / Time
๐ด "PFA" - pressure
P = F/A
Pressure = Force / Area
๐ฏ Scientists - Rules MATCH!
| Newton | Laws of Motion, Gravitation |
| Pascal | Uniform distribution of fluid pressure |
| Archimedes | Upward force (buoyancy) |
| Bernoulli | Velocity ↑ = Pressure ↓ |
| Einstein | E = mc² (atomic energy) |
๐ข Number Values โโ- QUICK MEMORY!
- g = 9.8 m/s²(acceleration of gravity)
- 1 N = 10โต dyne
- 1 J = 10โท erg
- 1 HP = 746 W
- 1 kWh = 3.6 × 10โถ J
- 1 atm = 76 cm Hg = 101325 Pa
- c = 3 × 10โธ m/s(speed of light)
โก Memory Trick - "746 HP"
๐ด "one horse = 746 watts"
7+4+6= 17 → 1+7 =8Legs (2 horse!)
๐ก To remember the number 746 → "7-4-6" three numbers!
๐ Unit conversion - MASTER TABLE
| measurement | SI | CGS | Change |
|---|---|---|---|
| key | N | dyne | 1N = 10โต dyne |
| Work/Energy | J | erg | 1J = 10โท erg |
| ability | W | erg/s | 1W = 10โท erg/s |
| Pressure | Pa | dyne/cm² | 1Pa = 10 dyne/cm² |
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