*12. �A golf ball strikes a hard, smooth floor at an angle of 30.0� and, as the drawing shows, rebounds at the same angle. The mass of the ball is 0.047 kg, and its speed is 45 m/s just before and after striking the floor. What is the magnitude of the impulse applied to the golf ball by the floor? (Hint: Note that only the vertical component of the ball�s momentum changes during impact with the floor, and ignore the weight of the ball.)

 

Look at momentum before and after

Let�s make up as + and down as -.� Since there are no forces acting in the x direction the momentum in the x direction is not changed.� But there is a force in the up y direction so the y momentum is changed. �Since the x component does not change and the angle does not change the y component must be the same in magnitude.� The impulse-momentum theorem provides�

 

 

 

From diagram we can see

and

 

 

 

 

 

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This page last updated on January 11, 2020