tan30o=ℓh
ℓ=h3=23m
WPQ=−μmgℓ or WQR=−μmgx
μmgℓ=μmgx
x=ℓ≈3.5m
x=23m
now according to work energy theorem
Wall=ΔK
mgh−μmgℓ−μmgx=0
h−μℓ−μx=0
2=μ(ℓ+x)⇒μ=ℓ+x2=432=231≈0.29
JEE Main 2016 — Physics Mechanics
2016mcqhard
A point particle of mass m, moves along the uniformly rough track PQR as shown in the figure. The coefficient of friction, between the particle and the rough track equals μ . The particle is released, from rest, from the point P and it comes to rest at a point R. The energies, lost by the ball, over the parts, PQ and QR, of the track, are equal to each other, and no energy is lost when particle changes direction from PQ to QR.
The values of the coefficient of friction μ and the distance x=(QR) , are respectively close to:
Official previous-year question
Held on 3 Apr 2016 · Verified 6 Jul 2026.
Options
- A
0.29 and 3.5 m
- B
0.29 and 6.5 m
- C
0.2 and 6.5 m
- D
0.2 and 3.5 m
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