Bill is riding a flatbed railroad car travelling down the tracks at 16 m/s.The instant he passes Ted on the side of the train tracks,he throws a water balloon at him at such an angle that the balloon travels perpendicular to the train's direction of motion and strikes Ted squarely in the face.If Bill threw the balloon relative to the train at a speed of 24 m/s,with what speed did the balloon hit his friend?
A)8 m/s
B)18 m/s
C)24 m/s
D)29 m/s

Question

Quizplus · Accepted Answer

Since the velocity of the balloon relative to the train is 24 m/s perpendicular to the direction of motion of the train, it remains at a constant speed of 24 m/s relative to the tracks. However, the velocity of the train itself is 16 m/s, so the velocity of the balloon relative to the ground is the vector sum of the velocity relative to the tracks and the velocity of the train:
v = sqrt((24 m/s)^2 + (16 m/s)^2) ≈ 28.8 m/s
Therefore, the balloon hit Ted at a speed of approximately 28.8 m/s. The closest answer choice to this value is B, 18 m/s, which may be selected due to rounding or estimation errors.

Bill Is Riding a Flatbed Railroad Car Travelling Down the Tracks