Biomechanics Ch 1-3
Tim and Ben sit on opposite sides of a playground seesaw. Tim sits 1.2m from the axis of the seesaw and Ben sits 1.5m from the axis of the seesaw. Tim's weight is 200N and Ben's body mass is 20kg. (use 9.8m/g2 of gravitational acceleration) (a) How much torque is created at the axis by Tim? (b) How much torque is created at the axis by Ben?
(a) 200N*1.2m = 240Nm (b) 20kg* (9.8m/s2)*1.5m = 294Nm
At take-off of a long jumper, the resultant velocity is 8m/s and take-off angle is 30° from the horizontal ground. Use the following trigonometry values (if needed) for calculation; sin30°=0.5, cos30°=0.87, tan30°=0.58 (a) what is the horizontal velocity of a long jumper? (b) what is the vertical velocity of a long jumper?
(a) 8m/s*cos30° = 6.96m/s (b) 8m/s "sin30° = 4m/s
A 1 cm long section of the Achilles tendon is 1 cm square in cross section. What is the stress in this tendon if it is subjected to a tensile force of 0.2 N?
2000 Pa
How much compressive stress is present on the L1 and L2 vertebra disc of a 600N woman, given that approximately 40% of body weight is supported by the disc when she stands in anatomical position? (Assume that the disc is oriented horizontally and that its surface area is 20 cm^2.)
F=600N*0.40=240N, Area = 20 cm^2 Stress = 240 N/20 cm^2 = 12 N/cm^2
Sarah is out for her daily run. She runs 3 km west, then 4 km south, and then runs on a path that takes her directly back to the place she started. a) how far did she run in Km? b) if she has run at an average speed of 4. m/s, how long did the entire run take in minutes?
a) 3 km+4 km+ 5 km = 12 km b) (12000m)/(4 m/s) = 3000s = 50 min
Gravitational force on planet X is 30% of that found on the earth. If a person weights 490N on earth (use 9.8m/s" of gravitational acceleration) (a) what is the person's weight on planet X? (b) what is the person's mass in [kg] on planet X?
a. 490N*0.3=147N b. 490N/(9.8m/s2) = 50kg
choose the term that describes the application of a single force of sufficient magnitude to cause injury
acute loading
Biomechanical research has contributed to which of the following? A. injury prevention B. enhanced sport performance C. equipment design D. all of the above
all the above
to obtain the least pressure... A. apply a small force spread over a large area B. apply a small force spread over a small area C. apply a large force spread over a large area D. apply a large force spread over a small area
apply a small force spread over a large area
Which of the following statement about the terms is incorrect? A. compression is types of force exerts a squeezing effect on the body B. torque is the rotary effect of a force C. stress is calculated the same as pressure D. bending is a load that produces twisting of a body around its longitudinal axis
bending is a load that produces twisting of a body around its longitudinal axis
a free body diagram includes which of the following? A. sketch of an object, body, or body part being analyzed B. vectors representations of all forces acting on the system C. both A and B D. None of above
both A and B
A bending force can result in which of the following types of stress?
both compression and tension
in a free body diagram of the human body, where would the vector representing weight of the body originate?
center of gravity
which of following is true regarding circumduction?
combines flexion, extension, adduction, and abduction
which of the following terms best describes translational motion along a curved line?
curvilinear
Which of the following is an incorrect pair of term and its unit? A. pressure, N/m2 B. impulse, N-s C. density, kg/m2 D. acceleration, m/s2
density, kg/m2
__________________ is used to describe the motion of bringing the foot closer to the lower leg
dorsiflexion
when a stretched material returns to its original shape, it's called:
elastic
deformation exceeding the structure's yield point produce mechanical failure of the structure
false
force is always a weight
false
pressure is synonymous with weight
false
torsion is the rotary effect of a force
false
which of the following is an incorrect pair of term and its unit? A. torque, N-m B. pressure, N/cm2 C. force, kg-m/s D. weight, N
force, kg/m^2
which of the following are all vector quantities? A. pressure, mass, acceleration B. force, pressure, weight C. force, torque, inertia D. density, acceleration, volume
force, pressure, weight
the frontal plane divides the body into equal ____________
front and back halves
abduction occurs in which plane?
frontal
which of the following is an incorrect pair of the glenohumeral joint movement and the plane of motion that movement can occur? A. abduction - frontal plane B. lateral rotation - transverse plane C. hyperextension - sagittal plane D. horizontal adduction - frontal plane
horizontal adduction - frontal plane
which of the following statement is incorrect? A. inertia is the tendency of a body to resist a change in its state of motion B. inertia is directly proportional to mass and unit of inertia is [g] C. mass is quantity of matter composing a body D. term that describes the mass per unit of volume is density
inertia is directly proportional to mass and unit of inertia is g
which of following terms means "farther from the head"?
inferior
which of the following characteristics of a vector represents magnitude? A. its angle of orientation B. its length C. its direction D. all of these answers are correct
it's length
_____________ is the term that describes the study of the description of motion, including considerations of space and time.
kinematics
which action is not an example of sagittal plane movement? A. flexion B. hyperextension C. lateral flexion D. plantar flexion
lateral flexion
which of following is/are pair (s) of terms and it's SI (metric) unit?
length, mm volume, liter pressure, Pa
movements in the transverse plane occur around which axis?
longitudinal
choose the term that describes the study of the action of forces A. Kinetics B. mechanics C. metric system D. qualitative
mechanics or kinetics
choose the term that describes "toward the midline of the body". A. medial B. posterior C. proximal D. rectilinear
medial
choose the term that describes "toward the back of the body".
posterior
choose the term that describes "involving a nonnumeric description of quality".
qualitative
Which imaginary cardinal plane bisects the body into right and left halves? A. sagittal B. frontal C. transverse D. None of these are correct
sagittal
Which of the following is an incorrect pair of terms of SI units? length - mm speed - ft/sec volume - liter pressure- Pa
speed- ft/sec
which of the following terms is applied to the study of systems in a constant state of motion? A. Dynamics B. Statics C. Anthropometrics D. Plyometrics
statics
in anatomical position, the forearm is in what position?
supinated
Which of following statement is not true? A. the knee is proximal joint relative to the ankle joint B. the shank is distal segment relative to the thigh C. the elbow is proximal joint relative to the shoulder joint D. the knee is distal joint relative to the hip joint
the elbow is proximal joint relative to the shoulder joint
Weight is always a force
true
anatomical reference position is when palms face forward, erect posture, starting position for describing motion
true
compression is types of force exerts a squeezing effect on the body
true
impulse is the product of force and the time over which the force acts
true
inertia is the tendency of a body to resist a change in its state of motion
true
mass is quantity of matter composing a body
true
shear force act parallel to a surface
true
stress is calculated the same as pressure
true
term that describes the mass per unit of volume is density
true
the knee is proximal joint relative to the ankle joint
true
the shank is distal segment relative to the thigh
true
torque is the rotary effect of a force
true
10kg ball in free fall is subjected to a crosswind exerting a force of 20N and to a vertical air resistance force of 38N. What is the square of magnitude of resultant force acting on the ball (use 9.8m/s? of gravitational acceleration)?
vertical : (9.8*10)N - 38N = 60N horizontal : 20N 60^2 + 20^2 = 4000