Which of the following is a good insulator? MCQ with Answer and Explanation

Explanation:
Total distance = 200 m (forward) + 100 m (back) = 300 m. Total time = 20 s + 10 s = 30 s. Average speed = total distance / total time = 300/30 = 10 m/s. Average velocity would be displacement (200-100=100 m) / 30 s = 3.33 m/s. But average speed is 10 m/s. Wait, 300/30 = 10. But that's option A 10 m/s. I need to check: Did I compute right? 200 m forward, then returns 100 m back, so total path length = 300 m. Time total = 30 s. Average speed = 10 m/s. Option A is 10 m/s, B is 6.67. That gives A. But to test concept, many confuse with velocity. I'll set correct answer A. But I'll adjust to make distinction: Maybe distance first 200 m at 10 m/s, return 100 m at 5 m/s? Already given times. So correct answer A. It's moderate. I'll keep.

Explanation:
Kepler's Second Law states that the line joining a planet to the Sun sweeps out equal areas in equal intervals of time (areal velocity is constant). Because the gravitational force is a central force (acting strictly along the radius vector), it exerts zero torque on the planet. When net torque is zero, angular momentum is strictly conserved.

Explanation:
Longer wire ⇒ smaller potential gradient (V/cm) ⇒ finer voltage measurement ⇒ higher sensitivity. Memory tip: 'Sensitivity ∝ wire length; smaller gradient = better resolution'. Experimental physics concept frequently tested in competitive exams.