Work Energy and Simple Machines — Class 9 Science NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 9 Science chapter "Work Energy and Simple Machines" — 8 important questions with detailed answers for CBSE board exam preparation.
✓ 100% Free
✓ No Login Needed
✓ NCERT / CBSE Aligned
✓ Download as PDF
TL;DR: Free step-by-step NCERT solutions for Class 9 Science chapter "Work Energy and Simple Machines" — 8 important questions with detailed answers for CBSE…
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
🤖 Stuck on any question? Ask Syllab's free AI Tutor for a step-by-step explanation — instant, unlimited, no login.
Key Questions Covered:
- Define work. When is work zero?
- Calculate work done by a 50 N force displacing an object 10 m in the directio…
- Define kinetic energy and potential energy.
- A 2 kg object moves at 3 m/s. Find its kinetic energy.
- Define power and write its formula.
- Calculate power if 100 J of work is done in 5 seconds.
- + 2 more questions in the full chapter
Solutions Summary:
| Question | Status |
|---|---|
| Define work. When is work zero? | ✓ Solved |
| Calculate work done by a 50 N force displacing an object … | ✓ Solved |
| Define kinetic energy and potential energy. | ✓ Solved |
| A 2 kg object moves at 3 m/s. Find its kinetic energy. | ✓ Solved |
| Define power and write its formula. | ✓ Solved |
| Calculate power if 100 J of work is done in 5 seconds. | ✓ Solved |
Showing 6 of 8 questions
Q1: Define work. When is work zero?
Work is the product of force and displacement in the direction of force.
Formula: W = F × d × cos θ
Where F = force, d = displacement, θ = angle between them
Work is zero when force is perpendicular to displacement (θ = 90°) or displacement is zero.
Q2: Calculate work done by a 50 N force displacing an object 10 m in the direction of force.
Step 1: F = 50 N, d = 10 m, θ = 0°
Step 2: W = F × d × cos(0°) = 50 × 10 × 1 = 500 J
Q3: Define kinetic energy and potential energy.
Kinetic energy is energy possessed by an object due to its motion.
Formula: KE = ½mv²
Potential energy is energy stored due to position or configuration.
Formula: PE = mgh (gravitational PE)
Both measured in Joules (J).
Q4: A 2 kg object moves at 3 m/s. Find its kinetic energy.
Step 1: m = 2 kg, v = 3 m/s
Step 2: KE = ½mv² = ½ × 2 × 3² = 1 × 9 = 9 J
Q5: Define power and write its formula.
Power is the rate of doing work or the rate of energy transfer.
Formula: P = W/t = E/t
Where W = work (J), E = energy (J), t = time (s)
Unit: Watt (W) = J/s
Q6: Calculate power if 100 J of work is done in 5 seconds.
Step 1: W = 100 J, t = 5 s
Step 2: P = W/t = 100/5 = 20 W
Showing 6 of 8 questions. Visit the full page for complete solutions.
More Class 9 Science NCERT Solutions
- Cell the Building Block of Life — Class 9 Science NCERT Solutions
- Tissues in Action — Class 9 Science NCERT Solutions
- Describing Motion Around Us — Class 9 Science NCERT Solutions
- Exploring Mixtures and Their Separation — Class 9 Science NCERT Solutions
- How Forces Affect Motion — Class 9 Science NCERT Solutions
- Journey Inside the Atom — Class 9 Science NCERT Solutions
- Atomic Foundations of Matter — Class 9 Science NCERT Solutions
- Sound Waves Characteristics and Applications — Class 9 Science NCERT Solutions
- Reproduction How Life Continues — Class 9 Science NCERT Solutions
- Patterns in Life Diversity and Classification — Class 9 Science NCERT Solutions
- Earth As a System Energy Matter and Life — Class 9 Science NCERT Solutions
- Matter Exemplar — Class 9 Science NCERT Solutions
- Atoms Molecules Exemplar — Class 9 Science NCERT Solutions
- Motion Exemplar — Class 9 Science NCERT Solutions
- Gravitation Exemplar — Class 9 Science NCERT Solutions