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Concepts Of Physics MCQ Edition [Volume 1]
Exam
Concepts Of Physics MCQ Edition [Volume 1]
Subject
Physics
Chapter
Rotational Mechanics

Concepts Of Physics MCQ Edition [Volume 1] · Physics · Rotational Mechanics

A force of 6.0 N applied at 30^ to a wrench at a distance of 8 cm...

A force of 6.0 N6.0 \text{ N} applied at 30∘30^\circ to a wrench at a distance of 8 cm8 \text{ cm} from the nut is just sufficient to loosen the nut. Determine the force FF that would be required to loosen it if it acts perpendicularly to the wrench at a distance of 16 cm16 \text{ cm} from the nut.
A force of 6.0 N applied at 30^ to a wrench at a distance of 8 cm from the nut is just sufficient to loosen the nut.

Options

  1. A12.0 N12.0 \text{ N}
  2. B6.0 N6.0 \text{ N}
  3. C3.0 N3.0 \text{ N}
  4. D1.5 N1.5 \text{ N}

Correct answer

D. 1.5 N1.5 \text{ N}

Step-by-step solution

The torque required to loosen the nut remains constant in both cases.

The torque τ\tau produced by a force is given by τ=rFsin⁡θ\tau = r F \sin \theta.

For the first case:
F1=6.0 NF_1 = 6.0 \text{ N}
r1=8 cmr_1 = 8 \text{ cm}
θ1=30∘\theta_1 = 30^\circ
τ1=8×6.0×sin⁡30∘=48×12=24 N cm\tau_1 = 8 \times 6.0 \times \sin 30^\circ = 48 \times \dfrac{1}{2} = 24 \text{ N cm}

For the second case:
F2=FF_2 = F
r2=16 cmr_2 = 16 \text{ cm}
θ2=90∘\theta_2 = 90^\circ
τ2=16×F×sin⁡90∘=16F N cm\tau_2 = 16 \times F \times \sin 90^\circ = 16F \text{ N cm}

Equating the torques:
τ1=τ2\tau_1 = \tau_2
24=16F24 = 16F
F=2416=1.5 NF = \dfrac{24}{16} = 1.5 \text{ N}
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