Which is always constant for a machine of given design: MA or VR ? Ans: VR remains constant for a machine of given design as it depends on the distances moved by the load and effort but MA can vary due to the friction developed between the moving parts of the machine.
Q: Why is uniform circular motion an accelerated motion? A: The velocity of Uniform Circular motion changes continuously due to its changing direction. As there is change in velocity, the motion is accelerated motion.
Question : Why are door handles fitted at the edge of the door ? Answer : Door handles are fitted at the edge to increase the perpendicular distance of the force from the axis of rotation so that the minimum force can be applied to achieve the given torque.
Q: Fog/ cloud appears white. Why ? Ans: Light is scattered by the fog particles. As the size of the particles is bigger than the wavelength of light, all colours are scattered to equal extent giving back white light. The property of light responsible for white clouds: scattering of light.
Convex lens can behave as a concave lens and vice versa when the lens is placed in a medium with refractive index more than that of the lens. Convex lens diverges and concave converges the rays.
Ans: The replica of an object formed by the intersection of reflected rays is called an image. Image is formed when the reflected rays actually meet at a point ( real image)or appear to meet( virtual image)