MIDTERM

Question 1

Torque (moment of force)

Answer 1

turning effect caused by a force (T=Fr),
perpendicular distance from axis of rotation to point of force application, change in orientation , counter = positive, clockwise = negative

Question 2

static equilibrium

Answer 2

all forces sum to 0, all torques in clockwise and counterclockwise direction sum to 0

Question 3

resultant of two or more torques

Answer 3

resultant is the sum of individual torques

Question 4

Determine if an object is in static equilibrium, when the forces/torques are known

Answer 4

add them up, if the sum of the forces and the sum of torques are 0 it is static equilibrium

Question 5

Determine an unknown force/torque if all other forces/torques are known and object is in static equilibrium

Answer 5

set the sum equal to 0, solve for unknown

Question 6

estimate the location of the center of gravity of an object or body

Answer 6

sum of torque = sum of the masses times the sum of the moment arms

Question 7

Define relative and absolute angular position, and distinguish between the two

Answer 7

relative = relative to a movable reference (another body segment
Ie: elbow angle (between arm and forearm)

absolute = relative to a set reference (the ground)
Ie: angle of the forearm with respect to the horizontal

Question 8

Torque eqn and units

Answer 8

T=F Xr
T(Nm)
F(N)
r(m)

Angular or rotary force

Question 9

Applying a force through the COG causes what type of motion

Answer 9

linear

Question 10

applying a force that is no directed through the COG causes what type of motion

Answer 10

linear and angular motion of the object

Question 11

applying a force that are equal and opposite in size, opposite in direction, and non-collinear will cause what type of motion

Answer 11

angular

Question 12

torque depends on

Answer 12

distance of the applied force from the center of gravity

distance of the force from the AOR

magnitude of applied for

Question 13

moment arm

Answer 13

perpendicular distance between the line of action of the force and a line parallel to it that passes through the AOR

Question 14

to fully describe a torque you must describe

Answer 14

1. the size of the torque (magnitude)
2. the axis about which the torque is create
3. the direction of the turning effect (cw, ccw)