• Nicole, a 70 kg volleyball player, lands on her feet after scoring an ace serve then immediately jumps up again to celebrate scoring. The instant before her feet first touch the floor after the serve, her velocity is 4.0 m/s downward. The vertical impulse exerted on her while she was in contact with the ground between landing and take-off was 441 Ns. The average vertical net force exerted on her while she was in contact with the ground was 1764 N.
• (a) What was Nicole's take-off velocity (vertical direction) when she jumped into the air to celebrate?
• (b) How long was Nicole in contact with the ground before she jumped into the air to celebrate? 
• (c) What was the average reaction force exerted upward by the floor on Nicole while she was in contact with the ground?
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