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Concepts Of Physics MCQ Edition [Volume 1]
Exam
Concepts Of Physics MCQ Edition [Volume 1]
Subject
Physics
Chapter
Newton's Laws of Motion

Concepts Of Physics MCQ Edition [Volume 1] · Physics · Newton's Laws of Motion

A monkey of mass 15 kg climbs a rope having one end fixed to the...

A monkey of mass 15 kg15 \text{ kg} climbs a rope having one end fixed to the ceiling. What force should it apply to the rope to ascend with an acceleration of 1 m/s21 \text{ m/s}^2? Furthermore, if the rope is 5 m5 \text{ m} long and the monkey starts from rest, how much time will it take to reach the ceiling? (Assume g=10 m/s2g = 10 \text{ m/s}^2)

Options

  1. A135 N135 \text{ N}, 10 s\sqrt{10} \text{ s}
  2. B150 N150 \text{ N}, 5 s\sqrt{5} \text{ s}
  3. C165 N165 \text{ N}, 5 s5 \text{ s}
  4. D165 N165 \text{ N}, 10 s\sqrt{10} \text{ s}

Correct answer

D. 165 N165 \text{ N}, 10 s\sqrt{10} \text{ s}

Step-by-step solution

Let TT be the tension in the rope, which is equal to the force applied by the monkey.

The equation of motion for the monkey moving upwards with acceleration aa is given by

T−mg=maT - mg = ma

T=m(g+a)T = m(g + a)

Substituting m=15 kgm = 15 \text{ kg}, g=10 m/s2g = 10 \text{ m/s}^2, and a=1 m/s2a = 1 \text{ m/s}^2:

T=15(10+1)=165 NT = 15(10 + 1) = 165 \text{ N}

To find the time taken to reach the ceiling, use the kinematic equation:

s=ut+12at2s = ut + \dfrac{1}{2}at^2

Given s=5 ms = 5 \text{ m}, u=0u = 0, and a=1 m/s2a = 1 \text{ m/s}^2:

5=0+12(1)t25 = 0 + \dfrac{1}{2}(1)t^2

t2=10t^2 = 10

t=10 st = \sqrt{10} \text{ s}
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