Tamil Nadu Class 9 Science Physics Unit Test — Samacheer Kalvi

Class 9 Science — Physics Unit Test

Time: 2 Hours | Marks: 50

Section A — 1 Mark (1 × 10 = 10)

1. What is the SI unit of pressure? 2. Define uniform motion. 3. What is the slope of a velocity–time graph? 4. State Pascal's law in one sentence. 5. What instrument measures the diameter of a thin wire? 6. Define least count. 7. What is the speed of sound in air at room temperature? (approximately 343 m/s) 8. What is Archimedes' Principle? (One sentence) 9. Define electric current. State its SI unit. 10. What is Ohm's Law?

Section B — 3 Mark (3 × 6 = 18)

(Choose 6 of 7)

1. Derive the first equation of motion: v = u + at using a velocity–time graph. 2. An object starts from rest and reaches 20 m/s in 5 s. Find: (a) acceleration, (b) distance covered. 3. State and explain Archimedes' Principle. Give one application. 4. Distinguish between speed and velocity with two examples each. 5. What are the conditions for an object to float, sink, or be in equilibrium in a liquid? 6. Explain how echo is produced. What is the minimum distance required to hear an echo? 7. Two resistors of 4 Ω and 6 Ω are connected in series. Find the total resistance.

Section C — 5 Mark (5 × 2 = 10)

(Choose 2 of 3)

1. Derive all three equations of motion graphically using a velocity–time graph. 2. Describe Archimedes' Principle and explain how it is applied in the working of ships. 3. Explain Pascal's Law with a hydraulic press diagram.

Section D — Numericals (1 × 12 = 12)

Solve with working:

1. A car starts from rest and accelerates at 3 m/s² for 8 seconds. Find: (a) final velocity, (b) distance covered. [v=24 m/s; s=96 m]

2. A body is moving at 10 m/s. It decelerates at 2 m/s². How long does it take to stop? What distance does it cover? [t=5s; s=25m]

3. An object with mass 5 kg is submerged in water. The volume of water displaced is 0.005 m³. Find the buoyant force. (Density of water = 1000 kg/m³, g = 10 m/s²) [50 N]

4. A wave has frequency 500 Hz and wavelength 0.68 m. Find its speed. [340 m/s]

End of Physics Unit Test

Marking Scheme:

• Section A: 1 mark each — no partial marks
• Section B: Award 1 mark per correct point (3 points per answer)
• Section C: 1 mark for method setup, 3 marks for correct working, 1 mark for final answer
• Section D: 1 mark for formula, 2 marks for working, 1 mark for final answer with units