Is the ratio between the sine of an angle of incidence to the sine of an angle of refraction is called the refractive index?

Plss anybody know how to do this? ? i need the answers from a through d

Abucket full of water weights 4 kg and water well is 10m deep. a girl draws water from the well. it takes the girl 3 minutes to draw a bucket full of water from the well. what is the power of the girl?

Alarge box of mass m is pulled across a horizontal frictionless surface by a horizontal rope with tension t. a small box of mass m sits on top of the large box. the coefficients of static and