💡 How to Calculate Percentage Error in Pressure Measurement – Class 11 Physics

📘 Question:

The pressure on a circular plate is measured by measuring the force on the plate and the radius of the plate. If the errors in measurement of the force and the radius are 5% and 3% respectively, the percentage of error in the measurement of pressure is?

🎯 Step-by-Step Explanation (As Your Favorite Physics Teacher Would Say)

Let’s make this unforgettable by keeping it super simple and practical.

1️⃣ What’s the Formula for Pressure?

Pressure on a circular plate is given by:

P = Force / Area = F / (πr²)

So, pressure depends on two quantities:

• Force (F)
• Radius squared (r²)

2️⃣ Percentage Error Rule (Golden Rule in Physics)

• When quantities are multiplied or divided, just add their percentage errors.
• When a quantity is raised to a power, multiply the error by that power.

3️⃣ Apply the Rule

Given:
➤ Error in Force (F) = 5%
➤ Error in Radius (r) = 3% ⇒ Radius squared means: 2 × 3% = 6%

✅ So, total error in Pressure = 5% + 6% = 11%

✅ Final Answer:

11% error in the measurement of pressure

🧠 How to Remember Forever (Physics Hack)

Imagine you're painting a round plate with a brush 🖌️. The pressure is how hard you press the brush, and the radius is how wide the plate is. If your force or radius measurements are off, the final paint job looks messy — just like the pressure calculation. So, always add the errors smartly!

🔍 Related Tags (For Learners & Exam Prep)

• Percentage error in physics formula
• Units and measurements Class 11 physics
• Error propagation in circular area
• How to calculate error in pressure
• NEET & JEE Physics – Units and Measurements