ME 577 – Human Motion Kinetics
Exam 1
Wherever possible use our four step method.
1.
Particle problem: A diver with a mass of 70 kg drops from a 10 meter platform with
an initial vertical velocity of 0 m/s. What is the diver’s vertical speed when he or she
impacts the water? How long does it take for the diver to hit the water?
Tomb of the Diver, Paestum, Italy (a Greek fresco dated to 470 BC).
2. Particle: Assume a fastball crosses the plate traveling horizontally at a speed of 22.1
m/s. To stop the ball, the catcher’s mitt (and the catcher’s arm) gives a little bit. The ball
is stopped over a distance of 0.15 m. Assume the catcher’s mitt exerts a constant force
on the ball. What is that force?
Twins catcher, Joe Mauer
3. Particle: Two ice skaters start out motionless in the center of an ice rink. They then
push each other apart. The male partner has a mass of 80 kg and moves to the left at a
speed of 1.5 m/s. If the female partner has a mass of 58 kg, how fast does she move?
Which direction does she move? What is the change in momentum of the two skaters?
What is the change in energy of the two skaters?
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4. Rigid Body (Pay attention to what is asked – we are not solving the entire problem): A
weight lifter starts with his hands at his sides and raises his arms 90
o
in T=1 second,
.
His arm is 80 cm long and rotates about the center of the humeral head. The deltoid
attaches at a point approximately 9 cm from the center of the humeral head. For simplicity,
assume that it always makes an angle of 10
o
with the long axis of the humerus. The weight
lifter raises a weight with a mass of 30 kg.
4a. Draw a free body diagram.
4b. Write out the equations of motion that govern the system.
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 Fall '09
 partner, cruciate ligament, dodge ball, Human Body, humeral head

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