A wire of resistance R is cut into three equal parts. These parts are then connected in parallel. The equivalent resistance is MCQ with Answer and Explanation

Explanation:
In third class lever, effort between fulcrum and load. Fishing rod, tweezers, forearm. Scissors first class, crowbar first/second, seesaw first. Mechanical advantage

Explanation:
On a frictionless surface, no net external force is required to maintain uniform velocity (Newton's first law). Only to change velocity force is needed. Thus, force required is zero. If friction present, force would be needed to balance friction.

Explanation:
Echo is the reflection of sound waves from a rigid surface, returning to the listener after a time delay. For distinct echo, minimum distance to reflector is about 17 m (so time delay > 0.1 s, persistence of hearing). Refraction bends sound in media with varying density; interference combines waves; diffraction bends around obstacles. Memory tip: 'Echo = sound reflection like light in mirror'. This application-based question links wave properties to daily-life phenomena, frequently tested in competitive exams to assess conceptual clarity beyond definitions. Always distinguish echo from reverberation (multiple reflections).