Forces and motion: Materials

Question 1

does it take equal forces to compress or extend a spring the same distance provided the spring constant is constant

Answer 1

Yes, extension and compression require the same for on identical springs

Question 2

define Hookes law

Answer 2

Extension is directly proportional to he force applied provided the elastics limit of the spring is not exceeded

Question 3

what is the equation of Hookes law

Answer 3

F=kx where k is the spring constant of the spring

Question 4

What is the equation of elastic potential

Answer 4

E=1/2kx^2

Question 5

describe the force extention graph of a metal wire

Answer 5

When loading, the graph follows Hookes law up to the elastic limit of the wire. For forces les than the elastic limit, the unloading graph is identical to the loading graph unless the force exceeds the elastic limit where the unloading graph is parallel to the unload graph but the wire had extended.

Question 6

Describe the force extension graph of rubber

Answer 6

the force extension graph does not abide to hookes law and will always return to its original shape unless the material breaks. the loop forms a hysteresis loop and more work is done when stretching a band than unloading it

Question 7

decribe the force extension graph of polytheme

Answer 7

does not obey hookes law they undergo deformation under relatively little force.

Question 8

define tensile stress

Answer 8

tensile stress is defined as the force applied per unit cross-section area of the material

Question 9

define tensile strain

Answer 9

tensile strain is defined as the fractional change in the original lenth of the wire

Question 10

how is the youngs modulus defined

Answer 10

YM=tensile stress/tensile strain

Question 11

what is the unit of young’s modulus

Answer 11

Pa