5
QuizMultiple Choice

Projectile Motion

Question 5 • [HSPHY] Physics Sem 1 (26-27)

Rhea is running towards Sean and kicks a soccer ball to him. Sean is standing still.

Answer
A
The speed of the ball from Sean’s reference frame would be greater than the speed of the ball from Rhea’s reference frame.
B
The speed of the ball from Sean’s reference frame would be less than the speed of the ball from Rhea’s reference frame.
C
The speed of the ball from Sean’s and Rhea’s reference frames would be 0 km/h.
D
The speed of the ball from Sean’s and Rhea’s reference frames would be less than 0 km/h.

Explanation

Sean is standing still, so his reference frame matches the ground’s frame. Rhea is running toward Sean in the same direction the ball travels, so the ball’s speed measured from Rhea is reduced by her own forward motion. Thus the ball is moving faster in Sean’s frame than in Rhea’s frame. The correct choice is A, the ball’s speed from Sean’s frame would be greater.

AI-written and checked against the verified answer.

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