Question

Statement I : For the planets orbiting around the sun, angular speed, linear speed, K.E. changes with time, but angular momentum remains constant.
Statement II : No torque is acting on the rotating planet. So its angular momentum is constant.

• A. If both statement I and statement II are true and statement II is the correct explanation of statement I
• B. If both statement I and statement II are true but statement II is not the correct explanation of statement I
• C. If statement I is true but statement II is false
• D. If both statement I and statement II are false

Answer 1

Answer: (A)

The torque on a body is given by $\vec{\tau} = \frac{d\vec{L}}{dt}$
In case of planet orbiting around sun no torque is acting on it.
$\frac{d\vec{L}}{dt} = 0$
$\Rightarrow \vec{L} = $ constant.