Chapter 2 - Forces, Circular Motion, and Gravitation

Question 1

Mechanical advantage of an inclined plane

Answer 1

1/sinθ

Question 2

Equation: angular acceleration given tangential acceleration

Answer 2

α = a/r

a = tangential acceleration

Question 3

How many degrees is 1 radian?

Answer 3

57.3º

Question 4

Equation: mechanical advantage

Answer 4

Mechanical advantage = weight of object supported/applied forced needed to support the object

Question 5

Equation: angular velocity, given period

Answer 5

ω = 2π/T

Question 6

Equation: Newton’s law of gravitation (Force) or Inverse Square Law

Answer 6

F = GM₁M₂/r²

Question 7

In what direction does centripetal acceleration point?

Answer 7

toward the center of a circle, perpendicular to the velocity

Question 8

Equation: centripetal force, given tangential velocity

Answer 8

F_c = m(v²/r)

Question 9

Kepler’s third law

Answer 9

Orbital period squared is equal to radius cubed.

Question 10

Which is greater: kinetic or static friction?

Answer 10

static friction

Question 11

As radius changes, does ω or v change?

Answer 11

V changes.

Tangential velocity increases as the radius increases, because you have to move farther to complete one revolution.

Question 12

Equation: Normal force on inclined plane

Answer 12

N = mgcosθ

Question 13

What is the equal and opposite force to centripetal force?

Answer 13

centrifugal force

Question 14

Equation: angle in degrees, given radians

Answer 14

θº = θradians (180º/π)

Question 15

Newton’s first law of motion

Answer 15

An object at rest remains at rest. An object in motion will continue to move with uniform velocity in a straight line, unless acted upon by an external force.

Question 16

Equation: angle in radians, given degrees

Answer 16

θradians = θº (π/180º)

Question 17

Equation: Newton’s second law (Net Force)

Answer 17

F = ma

Question 18

As the radius decreases, how does centripetal acceleration change?

Answer 18

A_c decreases, because tangential velocity decreases.

Question 19

Equation: circumference of a circle

Answer 19

2πr

Question 20

Kepler’s first law

Answer 20

All orbital paths are elliptical.

Question 21

Equation: friction

Answer 21

friction = µ_s/kN

µ = coefficient of friction

N = normal force

Question 22

Equation: centripetal acceleration, given angular velocity

Answer 22

a_c = ω²r

Question 23

What does an acceleration of so many g’s mean?

Answer 23

an acceleration of so many times the force of gravity

Question 24

Units of Newtons (N)

Answer 24

N = kg(m/s²)

Question 25

Mechanical advantage of a pulley is equal to what?

Answer 25

the number of vertical ropes (tensions) supporting the pulley

Question 26

How many radians make up a circle?

Answer 26

2π radians

Question 27

Equation: Kepler's third law

Answer 27

T² = (4π²/GM)R³ M = mass of orbited object

Question 28

Equation: Acceleration down an inclined plane

Answer 28

a = gsinθ

Question 29

Newton's second law of motion

Answer 29

A force acting on an object will give that object an acceleration in the direction of the force. The acceleration of the object is directly proportional to the resultant force applied and inversely proportional to the mass of the object.

Question 30

Newton's third law of motion

Answer 30

If one object exerts a force on a second object, the second object will exert a reactive force on the first object of equal magnitude, in the opposite direction.

Question 31

Kepler's second law

Answer 31

An orbiting object moves faster and is subject to a greater force when it is closer to the object about which it orbits.

Question 32

Equation: centripetal acceleration, given tangential velocity

Answer 32

a_c = v²/r

Question 33

Equation: Weight

Answer 33

W = mg

Question 34

Equation: angular velocity

Answer 34

ω = v/r v = tangential velocity

Question 35

Equation: time to complete revolution (Period), given frequency

Answer 35

T = 1/f