LECTURE #15 + 16 - angular kinematics

Question 1

what is angular motion ?

Answer 1

• rotation about a point
• within or outside body

Question 2

what are the three units to measure angels ?

Answer 2

1) degrees
2) revolutions or rotations
3) radian

Question 3

between degrees, revolutions/rotations and radians, which is the most common ?

Answer 3

degrees

Question 4

between degrees, revolutions/rotations and radians, which is used for qualitative analysis ?

Answer 4

revolutions or rotations

Question 5

between degrees, revolutions/rotations and radians, which is the most appropriate ?

Answer 5

radians

Question 6

1 radian = how many degrees ?

Answer 6

57.3 degrees

Question 7

what is a radian ?

Answer 7

ration of the arc length (r) of a circle to the radius length

Question 8

what is the formula for radians (θ) ?

Answer 8

arc length / r

Question 9

arc length & radius are units of length in what unit ?

Answer 9

meters

Question 10

TRUE OR FALSE

radian is a dimensionless measure ?

Answer 10

TRUE

Question 11

what are radians determined in multiples of ?

Answer 11

multiples of pi (3.14)

Question 12

1 radian = ?

Answer 12

57.3 degrees

Question 13

2 pi radians = ?

Answer 13

360 degrees

Question 14

what is angular distance ?

Answer 14

• total of all angular changes during its path of motion
• analogous to linear distance

Question 15

what is angular displacement ?

Answer 15

• difference between the initial and final position of a rotating object
• analogous to linear displacement
• indicate direction

Question 16

what is angular speed ?

Answer 16

angular distance traveled per unit of time

Question 17

what is angular velocity ?

Answer 17

• rate of change of angular displacement per unit of time
• direction depends on rotational direction

Question 18

what is angular acceleration (alpha) ?

Answer 18

rate of change in angular velocity

Question 19

what is an example of angular acceleration ?

Answer 19

throwing a baseball

Question 20

what is the relationship between linear and angular motion ?

Answer 20

motion of any point go a rotating body can be explained in linear terms (d = displacement)

Question 21

what do we need to know in the relationship between linear and angular motion ?

Answer 21

• axis of rotation
• radius f rotation (r) (distance from axis to point of rotation)
• kinematics in radians

Question 22

TRUE OR FALSE

for linear distance and angular displacement d=θr

Answer 22

TRUE

Question 23

what must θ be expressed in the units of for the expression to be valid ?

Answer 23

radians

Question 24

TRUE OR FALSE

radians are “unit-less”

Answer 24

TRUE

Question 25

if we see an increase in radius of rotation do we see an increase or decrease in linear displacement ?

Answer 25

increase

Question 26

TRUE OR FALSE

linear velocity of rotating object is non tangential (perpendicular) to path of motion ?

Answer 26

FALSE

linear velocity of rotating object is TANGENTIAL (perpendicular) to path of motion ?