Physics Ch 5

Question 1

Friction

Answer 1

force that is around us all the time that opposes relative motion between systems in contact but also allows us to move

Question 2

Kinetic friction

Answer 2

if two systems are in contact and moving relative to one another

Question 3

Static friction

Answer 3

when objects are stationary; this can act between them; usually greater than kinetic friction between objects

Question 4

Magnitude of static friction (fs)

Answer 4

fs </= usN, where us is the coefficient of static friction and N is the magnitude of the normal force (the force perpendicular to the surface)

Question 5

Magnitude of kinetic friction (fk)

Answer 5

fk = ukN, where uk is the coefficient of kinetic friction; friction behaves simply

Question 6

Drag force

Answer 6

always opposes the motion of an object; proportional to some function of the velocity of the object in a fluid; Fd is proportional to velocity squared

Question 7

Stokes’ Law

Answer 7

Fs = 6pi times radius times viscosity (n) times velocity (v)

Question 8

Deformation

Answer 8

change in shape due to the application of a force

Question 9

Hooke’s Law

Answer 9

F = proportionality constant (k) times the change in L (amount of deformation, change in length for example)

Question 10

Tensile strength

Answer 10

strength based on a given tension/compression

Question 11

Stress

Answer 11

ratio of force to area (N/m^2)

Question 12

Strain

Answer 12

ratio of change in length to length (unitless)

Question 13

Shear deformation

Answer 13

deformation perpendicular to the original length of an object