Physics Ch 6

Question 1

Uniform circular motion

Answer 1

motion in a circular path at constant speed

Question 2

Pure rotational motion

Answer 2

occurs when points in an object move in circular paths centered on one point

Question 3

Pure translational motion

Answer 3

motion with no rotation

Question 4

Rotation angle

Answer 4

ratio of the arc length to the radius of curvature

Question 5

Arc length

Answer 5

distance traveled along a circular path

Question 6

Radius of curvature

Answer 6

r of the circular path

Question 7

Radians

Answer 7

units used to measure rotation angles; 2pi rad = 1 revolution; ~57.3 degrees

Question 8

Angular velocity

Answer 8

rate of change of an angle in rads/s

Question 9

Centripetal acceleration

Answer 9

acceleration of an object moving in uniform circular motion (resulting from a net external force)

Question 10

Centrifuge

Answer 10

rotating device used to separate specimens of different densities

Question 11

Ultracentrifuge

Answer 11

centrifuges with very high centripetal accelerations

Question 12

Centripetal force

Answer 12

any net force causing uniform circular motion; direction is toward the center of curvature, the same as the direction of centripetal acceleration

Question 13

Banked curves

Answer 13

a curve where the slope of the road helps you negotiate the curve

Question 14

Ideal banking

Answer 14

the net external force equals the horizontal centripetal force in the absence of friction

Question 15

Non-inertial frame of reference

Answer 15

ex. a moving car, b/c it is accelerated to the side

Question 16

Fictitious force

Answer 16

a force sensed by someone/thing that has no physical origin

Question 17

Centrifugal force

Answer 17

a fictitious force that tends to throw an object off when the object is rotating in a non-inertial frame of reference

Question 18

Coriolis force

Answer 18

a fictitious force that can be used by anyone in that frame of reference to explain why objects follow curved paths & allows us to apply Newton’s Laws in non-inertial frames of reference

Question 19

Newton’s Universal Law of Gravitation

Answer 19

states that every particle in the universe attracts every other particle with a force along a line joining them; the force is directly proportional to the produce of their masses and inversely proportional to the square of the distance between them

Question 20

Center of mass

Answer 20

we assume that the body acts as if its entire mass is concentrated at one specific point called this

Question 21

Gravitational constant

Answer 21

G; a proportionality factor; a universal number equal to 6.673 x 10^-11 N m^2/kg^2

Question 22

Microgravity

Answer 22

refers to an environment in which the apparent net acceleration of a body is small compared with that produced by Earth at its surface

Question 23

Kepler’s First Law

Answer 23

the orbit of each planet about the sun is an ellipse with the sun at one focus

Question 24

Kepler’s Second Law

Answer 24

each planet moves so that an imaginary line drawn from the sun to the planet sweeps out equal areas in equal times

Question 25

Kepler’s Third Law

Answer 25

the ratio of the squares of the periods of any 2 planets about the sun is equal to the ratio of the cubes of their average distances from the sun

Question 26

Ideal angle

Answer 26

the angle at which a car can turn safely on a steep curve, which is in proportion to the ideal speed

Question 27

Ideal speed

Answer 27

maximum safe speed at which a vehicle can turn on a curve without the aid of friction between the tire and the road