Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
BITSAT 2024
Exam
BITSAT
Year
2024
Subject
Physics
Chapter
Work, Power and Energy

BITSAT 2024 · Physics · Work, Power and Energy

A pendulum of mass 1 kg and length l=1 ~m is released from rest at...

A pendulum of mass 1 kg and length l=1 ml=1 \mathrm{~m} is released from rest at angle θ=60∘\theta=60^{{}^{\circ}}. The power delivered by all the forces acting on the bob at angle θ=30∘\theta=30^{{}^{\circ}} will be \left(\right.Take,g=10 m/s2)Take, \left.g=10 \mathrm{~m} / \mathrm{s}^2\right)

Options

  1. A13.4 W
  2. B20.4 W
  3. C24.6 W
  4. Dzero

Correct answer

A. 13.4 W

Step-by-step solution

Power of tension =0=0 Power of  mg=(mg)(v)cos⁡60∘ Here, v=2gh and h=l(cos⁡30∘−cos⁡60∘)=0.36mv=2×10×0.36=2.68m/s Power =(mg)(v)cos⁡60∘=(1×10)(2.68)×12=1.34×10=13.4W\begin{aligned} & \text{ Power\text{ of } } m g=(m g)(v) \cos 60^{{}^{\circ}} \\ & \text{ Here, } \quad v=\sqrt{2 g h} \\ & \text{ and } \quad h=l\left(\cos 30^{{}^{\circ}}-\cos 60^{{}^{\circ}}\right)=0.36 \mathrm{ m} \\ & v=\sqrt{2 \times 10 \times 0.36} \\ & =2.68 \mathrm{ m} / \mathrm{s} \\ & \text{ Power }=(m g)(v) \cos 60^{{}^{\circ}} \\ & =(1 \times 10)(2.68) \times \frac{1}{2} \\ & =1.34 \times 10=13.4 \mathrm{ W} \end{aligned}$$
Practice Work, Power and Energy on Quantrex Academy →

More from Work, Power and Energy

All Work, Power and Energy questions Full Work, Power and Energy list All BITSAT PYQs