Suppose astronomers find an earthlike planet that is twice the size of earth (that is, its radius is twice that of earth’s). what must be the mass of this planet such that the gravitational force (fgravity) at the surface would be identical to earth’s?

While goofing off at the ice skating rink, a student takes off her shoes and places each of them on the ice. her friend, a hockey player, then shoots a hockey puck at each shoe. the first puck immediately comes to rest after it collides with the left shoe. the second puck rebounds after it collides with the right shoe. if each hockey puck has the same incoming speed, which shoe has greater speed after the collision? the right shoe. both shoes have the same speed. the left shoe.