The answer is d. most definitely.
Answer:
the awnser is A becuse the hair help.
From first law of motion, law of inertia, we know that an object remains in the state of rest or motion unless acted upon by an unbalanced external force. The skateboard riding down a hill when reaches the bottom slows down due to <u>frictional force </u>acting in the opposite direction. Frictional force is a contact force which acts between two surfaces against the direction of motion of one surface over the other. Here, frictional force acts <u>between skateboard and ground</u>. This reduces the speed of the skateboard and it eventually stops.
<span>If the pitch of a sound increased, then the wave frequency increased. (D)</span>
+2 electron charges = 2x1.6x10^-19Coulombs