⭐ CLASS 9 PHYSICS – WORK, ENERGY & POWER MASTER
SHEET
⚙️PART 1 – WORK
✅ 1. Work Done
⭐ Formula
W =F × s
(When force and displacement are in same direction)
⭐ Where to use
👉 Basic work numerical
👉 Push/pull problems
👉 Conceptual questions
⭐ Important condition for work
Work is done only when:
✅ Force acts
✅ Displacement occurs
✅ Force has component along displacement
⚠️Trap: holding bag → no displacement → no work
⭐ SI Unit
👉 Joule (J)
⚡ PART 2 – ENERGY
✅ 2. Energy
👉 Capacity to do work
Unit → Joule
, ⭐ 3. Kinetic Energy
⭐ Formula
1
KE= m v 2
2
⭐ Where to use
👉 Moving body problems
👉 Speed change questions
👉 Work–energy relation
⭐ NCERT Derivation (exam style)
Work done to change velocity from u to v:
W =Fs
Using motion equation:
2 2
v −u =2 as
Substitute:
1
W = m v2
2
⭐ 4. Potential Energy
⭐ Formula
PE=mgh
⭐ Where to use
👉 Height related energy
👉 Falling objects
👉 Energy conversion
⭐ Derivation idea
Work done against gravity:
SHEET
⚙️PART 1 – WORK
✅ 1. Work Done
⭐ Formula
W =F × s
(When force and displacement are in same direction)
⭐ Where to use
👉 Basic work numerical
👉 Push/pull problems
👉 Conceptual questions
⭐ Important condition for work
Work is done only when:
✅ Force acts
✅ Displacement occurs
✅ Force has component along displacement
⚠️Trap: holding bag → no displacement → no work
⭐ SI Unit
👉 Joule (J)
⚡ PART 2 – ENERGY
✅ 2. Energy
👉 Capacity to do work
Unit → Joule
, ⭐ 3. Kinetic Energy
⭐ Formula
1
KE= m v 2
2
⭐ Where to use
👉 Moving body problems
👉 Speed change questions
👉 Work–energy relation
⭐ NCERT Derivation (exam style)
Work done to change velocity from u to v:
W =Fs
Using motion equation:
2 2
v −u =2 as
Substitute:
1
W = m v2
2
⭐ 4. Potential Energy
⭐ Formula
PE=mgh
⭐ Where to use
👉 Height related energy
👉 Falling objects
👉 Energy conversion
⭐ Derivation idea
Work done against gravity:
