Read each statement and determine if it describes alpha, beta, or gamma decay,
decay occurs when a nucleus emits either an electron or a positron,
decay has no charge or mass but is capable of penetrating many substances,
decay has a charge of 2
decay results in a new element with the same mass number,
decay can be stopped by a piece of paper,

Alunar lander is making its descent to moon base i. the lander descends slowly under the retro-thrust of its descent engine. the engine is cut off when the lander is h = 5.5 m above the surface and has a downward speed of 0.8 m/s. with the engine off, the lander is in free fall. what is the speed of the lander just before it touches the surface? the acceleration due to gravity on the moon is 1.6 m/s2.