A student calculates the momentum of a toy car as it moves along a horizontal road. What would happen to the momentum of the car if the student doubled the mass of the car and reduced its speed by half?

You throw a small rock straight up from the edge of a highway bridge that crosses a river. the rock passes you on its way down, 7.00 s after it was thrown. what is the speed of the rock just before it reaches the water 28.0 m below the point where the rock left your hand? ignore air resistance.