BPK 142 Midterm: Biomechanics
SchoolSimon Fraser University
DepartmentBiomedical Physio & Kines
Course CodeBPK 142
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Week #6: Biomechanics
1. Which lever classes do a golf club, a swinging door, and a shovel belong to?
Explain your answers using a diagram, if necessary.
Golf club: 3 axis, force, resistance
Shovel: 3 axis, force, resistance
Swinging door: 2 axis, resistance, force
2. How much force must be produced by the biceps brachii, attached at 90 degrees
to the radius at 4.0 centimeters from the centre of rotation of the elbow joint, to
support a weight of 95 newtons held in the hand at a distance of 32 cm from the
elbow joint? Assume that the forearm and hand have a combined weight of 35
newtons and that their center of gravity is located 17 cm from the elbow joint.
FA = 4.0 cm
R = 95 N (weight)
RA = 32 cm
F x 4.0 cm = (95 N x 32 cm) + (35 N x 17 cm)
F = 908.75 N
3. Is the mechanical advantage of a first class lever greater than, less than, or equal
Depends. Can be either. If FA > RA, then >1. If FA < RA, then < 1. If FA = RA, then = 1.
4. Describe the various stance phase events and swing phase events during a gait
Heel strike: initiates stance phase. Heel hits floor.
Foot-flat: plantar surface of foot hits the ground.
Mid-stance: swinging foot passes stance foot.
Heel-off: heel loses contact with ground and push off is initiated by gastrocnemius and soleus
Toe-off: foot leaves ground
Acceleration: foot leaves ground. Hip flexor muscles accelerate leg forward.
Mid-swing: foot passes directly beneath the body.
Deceleration: muscles slow the leg and stabilize the foot.
5. As any runner changes from a slow running speed to a faster and faster running
speed he/she lands less flat-footed and more on the toes. Why?
- Lean forward 15 degrees, leans 15 degrees from the perpendicular
- Falling forward
- Increased velocity
- Acceleration phase emphasized
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