Apparent weight and elevator (በአማርኛ) Grade 9 Physics Unit 3 Part 3

Introduction

This tutorial provides a comprehensive overview of the concepts of apparent weight and true weight in the context of physics, particularly within the scenario of an elevator. Understanding these concepts is crucial for Grade 9 students as they explore the principles of motion and forces.

Step 1: Understand True Weight

True weight is the force exerted by gravity on an object. It can be calculated using the formula:

• Formula:
  • Weight (W) = mass (m) × acceleration due to gravity (g)
  • In most cases, g is approximately 9.81 m/s².

Practical Advice

• Make sure to measure your object's mass accurately.
• Remember that weight varies based on gravitational force, which can differ on other planets.

Step 2: Explore Apparent Weight

Apparent weight is the weight of an object as perceived in a specific condition, such as an elevator. It can change depending on the elevator's movement (accelerating up, accelerating down, or stationary).

Scenarios to Consider

1. Elevator at Rest or Constant Speed:

   • Apparent weight = true weight (W = mg)

2. Elevator Accelerating Upward:

   • Apparent weight increases.
   • Formula:
     • Apparent weight (W') = m(g + a)
     • Where a is the upward acceleration.

3. Elevator Accelerating Downward:

   • Apparent weight decreases.
   • Formula:
     • Apparent weight (W') = m(g - a)

Practical Advice

• Use a spring scale to measure the apparent weight in different scenarios to visualize the changes.

Step 3: Calculate Tension in the Cable

The tension in the elevator cable can be determined based on the movement of the elevator and the weight of the object inside.

Different Cases for Tension Calculation

1. When Elevator Accelerates Up:

   • Tension (T) = m(g + a)

2. When Elevator Accelerates Down:

   • Tension (T) = m(g - a)

3. When Elevator is at Rest or Moving at Constant Speed:

   • Tension (T) = mg

Practical Advice

• Use these formulas to solve problems involving different scenarios in exams or practical applications.

Conclusion

Understanding the concepts of true weight and apparent weight, along with calculating tension in various elevator scenarios, is essential for mastering the topic of forces in physics. To further your understanding, consider conducting experiments with weights in an elevator or similar setup, and practice problems related to these concepts. By applying these principles, you will strengthen your grasp of physics and prepare for future topics in your studies.