# TBR Physics: Section I, Passage VI, Q. 37

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#### circulus vitios

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Which of the following are likely differences between the golf clubs found in a golfer's bag?

I. The length of the club's shaft and size of its head.
II. The angle that the face of the club head makes with the ground when the shaft is perpendicular to the ground.
III. The weight of the club head.

A. I only.
B. I and II only.
C. I and III only.
D. I, II, and III.

I understand I and II are both answers. TBR's explanation for III makes no sense.

"Changing the weight of the club head will change the speed and kinetic energy of the head of the club it strikes the ball."

A golfer's hardest swing has a fixed amount of kinetic energy. Why would using a heavier or a lighter head (within the range of normal head weights) make a difference when the same kinetic energy is being put into the swing regardless?