A ball is moving 2.11 m/s at an angle of 37.0°
when it is hit by a racquet. The ball is in contact
with the racquet for 0.19 s. After, the ball moves
with a velocity of 3.80 m/s in a 150°
angle.
What is the magnitude of the acceleration of the ball?



Answer :

Answer:

  26.4 m/s²

Explanation:

You want the magnitude of the acceleration that changes a velocity of 2.11 m/s at 37.0° to 3.80 m/s at 150° in 0.19 seconds.

Acceleration

The acceleration is the change in velocity divided by the time.

  a = (3.80∠150° -2.11∠37.0° m/s)/0.19 s = 26.4∠173° m/s²

The magnitude of the acceleration is about 26.4 m/s².

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Additional comment

The magnitude of the velocity difference can also be found using the law of cosines:

  c² = a² +b² -2ab·cos(C)

  c = √(a² +b² -2ab·cos(C)) = √(3.80² +2.11² -2(3.80)(2.11)cos(150°-37·))

  c ≈ √25.1578 ≈ 5.0158 . . . . . |∆v|

Then the magnitude of the acceleration is ...

  (5.0158 m/s)/(0.19 s) ≈ 26.4 m/s² . . . . . |a| = |∆v|÷t

The angle of the acceleration, relative to one of the velocity vectors, can be found using the law of sines.

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