Joe (mass = 87 kg) hit a curb and was thrown from his bike. He hit the ground with a velocity of 11 m/s oriented 40 degrees relative to the horizontal, and came to rest 1.5 seconds after hitting the ground (ouch). [Hint: you can use Newton’s second law (F = ma), or Impulse-Momentum (Ft = mvf – mvi) to solve this problem]
What was the average horizontal force exerted by the asphalt on his body?

What was the average horizontal force exerted by the asphalt on his body?

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Joe's momentum hitting ground/asphalt = (87)(11) = 957 kgm/s at 40° from horizontal
The angle is 40° from horizontal, so the HORIZONTAL component of momentum is:
Mh = 957(cos 40°) = 733 kgm/s
The Horizontal Impulse of the ground/asphalt against Joe = Mh - 0 = 733 N-s
The average Horizontal force of ground/asphalt against Joe = 733/1.5 = 489 N ANS
The angle is 40° from horizontal, so the HORIZONTAL component of momentum is:
Mh = 957(cos 40°) = 733 kgm/s
The Horizontal Impulse of the ground/asphalt against Joe = Mh - 0 = 733 N-s
The average Horizontal force of ground/asphalt against Joe = 733/1.5 = 489 N ANS