<span>We can see that all these variable are always constant
EXCEPT acceleration. The rectilinear motion can only be applied if and only if
acceleration is CONSTANT.</span>
The type of radiation that can penetrate through paper, but not through wood is called beta rays. Beta rays can penetrate paper and air, but a thin piece of alimony can stop it. Gamma can cut through anything except lead and many inches of concrete. Alpha can be stopped by paper and not penetrated. The correct answer is B.