What instrument use lenses or mirrors to collect and focus light from distant objects?

Identical marbles are released from the same height on each of the following four frictionless ramps . compare the speed of the marbles at the end of each ramp. explain your reasoning

Anybody wanna ? (picture included? )

Find the equation for the plane through upper p 0 left parenthesis negative 4 comma negative 8 comma negative 5 right parenthesis perpendicular to the following line. xequalsnegative 4 minus t, yequalsnegative 8 plus 2 t, zequals3 t, minusinfinityless thantless thaninfinity