Lecture 19 - Angular Kinetics : Torque and Rotation

Question 1

the type of motion we observe is indicative of the

Answer 1

way the force is applied

Question 2

what is general motion

Answer 2

a combination of both rotational and translational motion, most motion is this

Question 3

what is rotational motion

Answer 3

Rotation occurs when an object moves in a circular path around a fixed axis

Question 4

what is translational motion

Answer 4

There is no rotation; the object moves linearly.

Question 5

in human motion all internal forces are

Answer 5

rotational

Question 6

a force through the centre of mass will cause

Answer 6

translation, this generates linear motion

Question 7

a force NOT through the centre of mass (eccentric force) will cause

Answer 7

rotation, not just translation (turning effect we call torque)

an eccentric force generates both linear and angular motions

Question 8

force can cause rotation but the amount of torque is dependent on (and example)

Answer 8

the moment arm

e.g how far away the force is from the hinge of a door

Question 9

torque is influenced by

Answer 9

• magnitude of force
• line of action of the force (direction)
• point of application of the force

Question 10

in terms of torque, the distance (r) is always measured…

Answer 10

perpendicular

i.r at right angles or 90deg to the line of action of the force

Question 11

for torque the axis of rotation can be fixed like

Answer 11

• the hinges on a door
• your forearm is fixed to your elbow axis

Question 12

for torque the axis of rotation can be free like

Answer 12

your centre of mass

Question 13

in the right hand rule, fingers are in the direction of

Answer 13

force

i.e direction of rotation

Question 14

in the right hand rule, thumb points in the direction of

Answer 14

torque vector

i.e perpendicular to plane of rotation

Question 15

clockwise rotation is

Answer 15

negative

Question 16

counter clockwise rotation is

Answer 16

positive

Question 17

what is the sum of torques

Answer 17

the net turning effect on an object is equal to the sum of the torques

Question 18

what is the torque equation

Answer 18

T = Fr

Question 19

if the size and direction of the forces acting on an object are exactly balanced, then ….

Answer 19

there is no net force acting on the object and the object is said to be in equilibrium

Question 20

in terms of equilibrium

… from Newtons first law of motion, an object at rest will……… and an object in motion will

Answer 20

an object at rest will stay at rest and an object in motion will stay in motion