Projectile Motion Golf Question

[michaeljf]

Homework Statement

Not too long ago, an interesting thing happened at the Canadian Open Golf Tournament. Tiger Woods bounced his tee shot off of a young spectator’s head in the last round of the tournament. The ball made contact for 0.08 seconds, and struck the boy’s head at a velocity of 32 m/s, 25degree from a tangent on the surface of his cranium. It bounced off at an angle of 22degree, with a speed of 25 m/s. What was the average acceleration of the ball as it amazingly made its way back onto the fairway?

I have no idea on how to start this.

Homework Equations

The Attempt at a Solution

 

[ideasrule]

What's the difference between the final velocity of the ball and its initial velocity? Remember that acceleration is just change in velocity divided by change in time.

 

[Delphi51]

Welcome to PF, Michael.
Not a particularly clear question! I would be tempted to answer that the acceleration is -9.81 m/s² as it "makes its way back onto the fairway" but I suppose the question really means the acceleration while in contact with the boy's head. There are 2D directions involved so you need a diagram sorting out those angles and you need to calculate the acceleration in each of the two dimensions and then get a combined value. Just use a = Δv/Δt.

 

[michaeljf]

Welcome to PF, Michael.
Not a particularly clear question! I would be tempted to answer that the acceleration is -9.81 m/s² as it "makes its way back onto the fairway" but I suppose the question really means the acceleration while in contact with the boy's head. There are 2D directions involved so you need a diagram sorting out those angles and you need to calculate the acceleration in each of the two dimensions and then get a combined value. Just use a = Δv/Δt.

I thought in projectile motion, the horizontal velocity does not change, thus a = 0 and its 9.81 for the vertical component?

 

[Delphi51]

That's true for the free flight (neglecting air resistance).
But my theory is that you are asked for the acceleration when the head is exerting a force on the ball. I haven't drawn the diagram, but since the angle with the head changes, I suspect the ball changes speed in both the direction perpendicular to the head and the direction parallel to it.