Can we get off a frictionless horizontal surface by jumping?

A small body of mass m slides down from the top of a frictionless hemispherical surface of radius r as shown in the figure.The vertical height h below the highest point at which the body gets separated from the hemispherical surface. .

A body is moving at constant speed over a frictionless surface. What is the work done by the weight?

A liquid surface is horizontal. why?

Why can we not get diffraction from a wide slit illuminated by a monochromatic light?

What do we get on the combustion of natural gas?

Can we divide a vector by vector?

What do we get when starch is hydrolysed?

A girl of 40 kg mass jumps with a horizontal velocity of 5ms'1 on a stationary trolley. The wheels of the skate are frictionless. What will be the velocity of the girl in the position of start of the trolley. Suppose no unbalanced force is acting in the horizontal direction.(mass of trolley is 3 kg)