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AP® Physics 1 & 2

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Relative Train Motion

APPH12-WU8VID

Train A and Train B are traveling near one another on parallel tracks.

The conductor of Train A hears Train B's whistle, and (being familiar with the sound of train whistles), notes that it sounds lower pitch than usual.

Which of the following are valid conclusions that the conductor could draw from this observation?

Select TWO answers.

A

The trains are travelling in the same direction and are both travelling at the same speed.

B

The trains are travelling in the same direction, train A is ahead of train B, and train A is moving faster than train B.

C

The trains are travelling in opposite directions and have already passed each other.

D

The trains are travelling in opposite directions and are just about to pass each other.