Final Exam

Question 1

rotary effect of a force about an axis of rotation

Answer 1

torque

Question 2

product of force and the forces moment arm

Answer 2

torque

Question 3

shortest(perpendicular) distance between a force line of action adn an axis of rotation

Answer 3

forces moment arm

Question 4

muscles moment arm is maximal at ___ degree angle of pull

Answer 4

90

Question 5

the moment arm of muscle pull becomes ___ at the line moves away from 90 degree in either direction

Answer 5

smaller

Question 6

for muscle to generate a constant torque during an exercise, it must produce ___ force at its moment arm decreases

Answer 6

more

Question 7

The product of muscle tension and muscle moment arm produces a torque at the ___ crossed by the muscle.

Answer 7

joint

Question 8

simple machine consisting of a relatively rigid bar-like body that can be made to rotate about an axis or fulcrum

Answer 8

lever

Question 9

levers come in what classes

Answer 9

first, second, and third

Question 10

lever classification is determined by what

Answer 10

applied force, resistance, and the fulcrum or axis of rotation

Question 11

fulcrum in the middle with equal distance on each side to the applied force and resistance

Answer 11

first class lever

Question 12

lever with axis of rotation on the outside of resistance (resistance down, applied force up

Answer 12

second class lever

Question 13

lever with axis of rotation on the outside of the applied force (applied force up and resistance down)

Answer 13

third class lever

Question 14

Tilting head is what class of lever

Answer 14

first class

Question 15

class of lever when going on tippy toes

Answer 15

second class

Question 16

class of lever with an elbow bend

Answer 16

third class

Question 17

point around which a body’s weight is equally balanced in all directions

Answer 17

center of gravity

Question 18

center of mass of mass centroid

Answer 18

center of gravity

Question 19

is the center of gravity always inside the body

Answer 19

no

Question 20

the point at which the weight vector is shown to act in a free body diagram

Answer 20

center of gravity

Question 21

the body responds to external forces as though all mass were concentrated at the ___

Answer 21

center or gravity

Question 22

resistance to disruption of equilibrium

Answer 22

stability

Question 23

ability to control equilibrium

Answer 23

balance

Question 24

area bound by the outermost regions of contact between a body and the support surface

Answer 24

base of support

Question 25

what increases a body's stability

Answer 25

- increasing body mass, and --increasing friction between the body and the surfaces of contact - increasing the size of the base of support in the direction of an external force - horizontally position the CG near the edge of the base of support on the side of external force - vertically positioning the CG as low as possible

Question 26

Higher the CG the ___ the amount of torque its motion creates about the support surface

Answer 26

greater

Question 27

the ratio of the moment arm of the force to the moment arm of the resistance for a given lever

Answer 27

mechanical advantage

Question 28

moment arm (force)/ moment arm (resistance)=

Answer 28

mechanical advantage

Question 29

Whenever the moment arm (force) is ____ than the moment arm (resistance) the magnitude of the applied force required to move the resistance is ___ than the magnitude of the resistance

Answer 29

greater, less

Question 30

___ mechanical advantage, the ___ force needed

Answer 30

greater, less

Question 31

a force can balance a ___ resistance when the force arm is_____ than the resistance arm

Answer 31

larger, longer

Question 32

force can move a resistance through a large range of motion when the force arm (Fa) is _____ than the resistance arm (Ra).

Answer 32

shorter

Question 33

what class of lever is most common in the human body

Answer 33

third class

Question 34

torque causing a body segment to rotate may be modified by changing either___ or _____

Answer 34

force or moment arm

Question 35

in the body, weight of a segment ___ be altered instantaneiously

Answer 35

cannot

Question 36

torque of a segment due to gravitational force can be changed only by changing nthe ___ of the moment arm

Answer 36

length

Question 37

muscle force that exert ___ are dependent on point of insertion of the muscle and changes in length, tension, and angle of pull

Answer 37

torque

Question 38

net moment or resultant joint torque

Answer 38

net torque

Question 39

sum of all external torques acting on the system

Answer 39

net torque

Question 40

what will net muscle moment determine

Answer 40

resulting motion, type of muscle action ** does not indicate how much force is produced by each muscle

Question 41

a motionless state in whcih there is no net force or net torque acting

Answer 41

static equilibrium

Question 42

the sum of all forces must be ___ for static equilibrium

Answer 42

zero

Question 43

resistance to linear acceleration

Answer 43

inertia (proportional to its mass)

Question 44

resistance to angular acceleration

Answer 44

dependent on the mass's distribution in relation to the axis of rotation

Question 45

sum of the products of the mass element of an object and the square of the distance between the mass element and the axis of rotation

Answer 45

inertia

Question 46

factors that affect angular momentum

Answer 46

mass of object, distribution of mass relative to axis of rotation, angular velocity of the object

Question 47

in the absence of external torques, ___ is conserved

Answer 47

H

Question 48

angular impulse is required to change

Answer 48

H

Question 49

____ force is require for an object to rotate

Answer 49

centripetal