Pseudo Force (non-inertial Frames)
Mediumphysics
In an accelerating car (a = 4 m/s² forward), a pendulum bob of mass 0.2 kg hangs at equilibrium making an angle θ with the vertical. Neglect air resistance. Find tan θ.
Select the correct option:
Solution
Incorrect! Answer:
0.40
- Analyze in Non-Inertial Frame: For an observer inside the accelerating car, the bob is in equilibrium, but a pseudo force must be added.
- Forces on Bob:
- Weight: mg downwards.
- Pseudo Force: ma backwards (opposite to car acceleration).
- Tension: T along the string.
- Equilibrium Equations:
- Vertical: Tcosθ=mg
- Horizontal: Tsinθ=ma
- Divide Equations: TcosθTsinθ=mgma⟹tanθ=ga.
- Substitute Values: tanθ=104=0.40.
- Final Result: The tangent of the angle is 0.40.
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About This Question
- Subject
- physics
- Chapter
- laws of motion
- Topic
- pseudo force (non-inertial frames)
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
0.40
- Analyze in Non-Inertial Frame: For an observer inside the accelerating car, the bob is in equilibrium, but a pseudo force must be added.
- Forces on Bob:
- Weight: mg downwards.
- Pseudo Force: ma backwards (opposite to car acceleration).
- Tension: T along the string.
- Equilibrium Equations:
- Vertical: Tcosθ=mg
- Horizontal: Tsinθ=ma
- Divide Equations: TcosθTsinθ=mgma⟹tanθ=ga.
- Substitute Values: tanθ=104=0.40.
- Final Result: The tangent of the angle is 0.40.
This medium difficulty physics question is from the chapter laws of motion, covering the topic of pseudo force (non-inertial frames). It appeared in the 2025 exam.
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