E Fields 3

Electron in E Field

Frog

Pressure Answers

Experiment with Scales and Charged Rods

E Filed Calculations

E Field and a Bunsen Burner

Gravitational Field Lines

Gravitational Field Strength

G and Centripetal Force

Inverse Square Law

Earth - moon

Young's Modulus - Past questions

     (a)     (i)      Stress = force / area                                                                              C1

force = stress ´ area

 = 180 ´ 106 ´ 1.5 ´ 10–4

 = 27000 (N)                                                                                 A1

(ii)     Y M = stress / strain                                                                              C1

= 180 ´ 106 / 1.2 ´ 10–3 or using the gradient                               C1

= 1.5 ´ 1011 N m–2                                                                       A1

  (b)   brittle

elastic/ graph shown up to elastic limit

obeys Hooke’s law / force α extension / stress α strain

no plastic region                                                                                             B3

MAX 3

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     cast iron:     brittle
                   brittle explained as having no plastic region
                   elastic
                   elastic explained as returning to original length when
                   the load is removed / linear graph / Hooke’s law obeyed
                   or equivalent words                                                                       MAX 3

          copper:       ductile
                   ductile explained as can be formed into a wire
                   initially elastic
                   plastic where it stretches more and more with little
                   increase in stress
                   plastic explained as does not return to its original length
                   when the load is removed
                   reference to necking at the end                                                      MAX 3

          polythene:  easy to deform / deformed with a small force
                   plastic
                   ductile
                   polymeric                                                                                      MAX 2

                                                                                                                                  MAX 8

          QWC:        spelling, punctuation and grammar                                                    B1
                   organisation and logic                                                                         B1

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