What is the speed of light?

Abody of weight 60 kg is standing in a lift the lift going upward with a uniform velocity of 4.9 metre per second slows down and stops in two seconds then apparent weight of the body during the slow down process is

Atrain departs from its station at a constant acceleration of 5 m/s. what is the speed of the train at the end of 20s?

People with normal vision cannot focus their eyes underwater if they aren't wearing a face mask or goggles and there is water in contact with their eyes. in a simplified model of the human eye, the aqueous and vitreous humors and the lens all have a refractive index of 1.40, and all the refraction occurs at the cornea, whose vertex is 2.60 cm from the retina. with the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 2.05cm in front of the eye.)