Science of Sport
TESC – winter 2003
Please answer all of the following questions, and
submit them no later than Monday, February 24th.
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The Achilles tendon [calcaneal tendon] inserts on the calcaneus [heel bone]
at a distance of 8 cm from the axis of the ankle joint. If
the force generated by the muscles attached to the Achilles tendon is 3000N
& the moment arm of this force about the ankle joint axis is 5 cm,
what torque is created by these muscles about the ankle joint? Please
show equation.
-
Two athletes perform strict biceps curls with 30 lb dumbbells. One athlete
has much longer forearms. Why
does the biceps curl demand more muscular force from the athlete with the
longer forearms?
-
An Olympic weightlifter weighing 234 lb stands erect with his feet together
and with a 400 lb barbell at arm’s length above his head. Why
is it difficult for the weight lifer in this situation to maintain a state
of equilibrium and control the barbell?
4. When you pedal a bicycle, maximum torque is produced
when the pedal sprocket arms are in the horizontal position and practically
no torque is produced when they are in the vertical position. Explain.
5.Sometimes
a kicked football sails thru the air without rotating, and at other times
it tumbles end over end as it travels. With
respect to the center of mass of the ball, how is it kicked in both cases? [hint
–think about where on the ball it is kicked]
6.Why
is less effort required in doing sit-ups when your arms are extend in front
of you? Why is it more difficult
when your arms are placed in back of your head?
7.Where is
the center of mass of a baseball? Where is its center of gravity?Where
are these centers for a baseball bat?