Laws of MotionHard
Question
A particle of small mass m is joined to a very heavy body by a light string passing over a light pulley. Both bodies are free to move. The total downward force on the pulley is nearly
Options
A.mg
B.2 mg
C.2 mg
D.can not be determined
Solution

Mg − T = Ma [ Newton′s II law for M]
T − mg = ma [ Newton′s II law for m]
⇒ T =
If m << M than m + M ≈ M
⇒ T =
⇒ T = 2 mg
Total downward force on pulley is 2T = 4 mg.
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