Constraint Motion (two Bodies)
Hardphysics
Two blocks connected by an inextensible string over a frictionless pulley: m1 = 8 kg on a frictionless horizontal table, m2 = 2 kg hanging. Find the acceleration of the system (g = 10 m/s²).
Select the correct option:
Solution
Incorrect! Answer:
2 m/s²
- Identify Forces:
- On m1 (Table): Tension (T) pulls it forward.
- On m2 (Hanging): Weight (m2g) pulls it down, Tension (T) resists.
- Write Equations (F=ma):
- Table block: T=m1a⟹T=8a.
- Hanging block: m2g−T=m2a⟹20−T=2a.
- Substitute T:
- 20−(8a)=2a
- 20=10a
- a=2 m/s2.
- Common Trick: The hanging weight is the ONLY external force driving the whole system mass: a=m1+m2m2g=1020=2 m/s².
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About This Question
- Subject
- physics
- Chapter
- laws of motion
- Topic
- constraint motion (two bodies)
- Difficulty
- Hard
- Year
- 2025
Solution
Correct Answer:
2 m/s²
- Identify Forces:
- On m1 (Table): Tension (T) pulls it forward.
- On m2 (Hanging): Weight (m2g) pulls it down, Tension (T) resists.
- Write Equations (F=ma):
- Table block: T=m1a⟹T=8a.
- Hanging block: m2g−T=m2a⟹20−T=2a.
- Substitute T:
- 20−(8a)=2a
- 20=10a
- a=2 m/s2.
- Common Trick: The hanging weight is the ONLY external force driving the whole system mass: a=m1+m2m2g=1020=2 m/s².
This hard difficulty physics question is from the chapter laws of motion, covering the topic of constraint motion (two bodies). It appeared in the 2025 exam.
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