Materials

Question 1

Explain to me why does polythene suffer plastic deformation

Answer 1

when polythene is under tension and is stretched, cross links between molecules are broken and new ones form in the stretched state. And when the tension is removed, the polythene remains stretched

Question 2

What occurs at the yield point?

Answer 2

the wire weakens temporarily

Question 3

What occurs at the elastic limit?

Answer 3

the wire is permanently stretched and suffers plastic deformation

Question 4

What occurs beyond the ultimate tensile stress (UTS)

Answer 4

the wire loses its strength, extends and becomes narrower at its weakest point

Question 5

What is tensile stress?

Answer 5

tension per cross-sectional area …….. = T/A

Question 6

What is tensile strain?

Answer 6

extension per unit length ……. =Al/L

Question 7

What can be said about the area under the curve (line) of a force against extension graph?

Answer 7

it is equal to the work done and Elastic potential energy stored in a stretched spring

Question 8

What can be said if a spring is stretched beyond its elastic limit?

Answer 8

it does not regain its initial length when the force applied to it is removed

Question 9

How can you measure the stiffness of a material using a stress/strain graph? And what is it equal to?

Answer 9

the gradient of the line. Which is equal to the young modulus

Question 10

What can the kaon decay into?

Answer 10

1. Two Pions
2. A muon and an antineutrino
3. An antimuon and a neutrino

Question 11

What can a charged pion decay into?

Answer 11

1. A muon and an antineutrino
2. Antimuon and a neutrino
   3 a neutral pion decays into high energy photons