Chapter 2

Question 1

force

Answer 1

an interaction of some sort that can cause an object to accelerate

Question 2

units for force

Answer 2

Newton (N) = SI unit

N = kg•m/s²

Question 3

gravitational force

Answer 3

this force acts on mass at a distance

Question 4

electromagnetic force

Answer 4

most likely to appear in electrostatic problems

Question 5

contact/pushing force

Answer 5

force you can exert by pushing an object horizontally

Question 6

normal force

Answer 6

the force that surfaces exert in response to gravity

Question 7

friction

Answer 7

the force that pushes back against horizontal movement

Question 8

tension

Answer 8

the force exerted on an ideal string

Question 9

centripetal force

Answer 9

any force that makes an object follow a curved path

Question 10

force applied to strings

Answer 10

Hooke’s law (F = -kx)

Question 11

Newton’s first law

Answer 11

statment about inertia

within a reference frame, an object remains at rest or at a constant velocity unless an external force acts upon it

F_net = 0 at equilibrium

Question 12

Newton’s second law

Answer 12

defines force

F_net = m•a

Question 13

Newton’s third law

Answer 13

how forces come in pairs

Every action has an equal and opposite reaction

F_ab = -F_ba

Question 14

free-body diagram

Answer 14

representation of all the forces acting on an object

Question 15

center of mass using reference point when more than 1 mass is being studied

Answer 15

x_center= m₁x₁ + m₂x₂…/ m₁ + m₂…

Question 16

static friction

Answer 16

applies when we are pushing an object and it doesn’t move because the applied force is less than a threshold that is defined as F_max= µ_sN_s where µ_s is the coefficient of static friction and N is the normal force of the object

F_applied less than or equal to F_max

Question 17

kinetic friction

Answer 17

once the object is put into motion F_max is greater than F_max (=µ_sN)

kinetic friction is a specific property of the material an object is made out of and the surface an object is sliding across

remains constant as the applied force increases and is present if the applied force suddenly stops

F_kinetic= µ_kN

Question 18

air resistance (drag)

Answer 18

opposes the direction of the objects motion

affected by density of the air, velocity of the object, cross-sectional area of the object, and a drag coefficient’eventually drag will equal the force of gravity so it can no longer accelerate = terminal velocity

Question 19

box on incline plane

Answer 19

F = ma

Question 20

force of gravity between 2 objects

Answer 20

F_grav= G(m₁m₂/r²)

Question 21

centripetal acceleration is

Answer 21

a = v²/r

F_c = mg = mv²/r which simplifies to g = v²/r

Question 22

Hooke’s law

Answer 22

F_spring= -kx

k is the spring constant and is unique for each spring and has units of N/m

greater k units mean that more force is necessary to deform a spring by a certain amount = stiffer

Question 23

torque

Answer 23

t= F•d•sin(theta)

torque refers to rotational force. caused by force applied to a lever arm at a certain distance from an object capable of rotating around a fulcrum

Question 24

3 ways torque can be increased

Answer 24

increased force, increased distance from the fulcrum, and as close to 90 degrees as possible

Question 25

direction of torque

Answer 25

Counterclockwise is the positive rotation direction of torque clockwise is the negative direction of torque

Question 26

energy

Answer 26

what accomplishes work

Question 27

work is defined in units of

Answer 27

Joules

Question 28

1 J =

Answer 28

N•m (1 Newton of force applied across 1 meter)

Question 29

1N = 1kg•m/s² then 1J =

Answer 29

1 kg•m/s²/s²

Question 30

work is a what kind of quantity

Answer 30

vector quantity

Question 31

Work =

Answer 31

F•d•cos(theta) - occasions where sine will be used

Question 32

conservative forces

Answer 32

* path independent * the amount of work done by a conservative force does not depend on its path * care about displacement for conservative forces

Question 33

types of conservative forces

Answer 33

* graviation * electromagnetic forces * spring forces

Question 34

non-conservative forces

Answer 34

* exacting a certain energetic cost per distance * path-dependent

Question 35

types of non-conservative forces

Answer 35

* air resistance * friction

Question 36

work = force • distance only works for?

Answer 36

* constant forces

Question 37

area under the curve of a force vs displacement graph =

Answer 37

work

Question 38

for ramps, the ideal mechanical advantage can be calculated by:

Answer 38

MA = length of incline/ heigh of incline

Question 39

F_in • d_in =

Answer 39

F_out • d_out

Question 40

Power

Answer 40

work divided by time

Question 41

units of power

Answer 41

Watts = J/s

Question 42

work also equals

Answer 42

P • (deltaV)

Question 43

idea of power is?

Answer 43

* essentially that a given amount of work could be expended either quickly or slowly, and that a system capable of doing so quickly is more "powerful"

Question 44

Power also equals

Answer 44

F•v (velocity) and can be applied to situations where energy must be applied to keep an object travelling at a certain velocity despite the presence of a force opposing that motion, such as friction