iGCSE Physics: June 2013

Monday 10 June 2013

Markscheme for homework

1. (a) F = m × a / W = m × g;
= 70 × 10;
= 700 N; 3

(b) speed constant;
upward force = downward force/
forces balanced/from F = ma if a = 0; 2

(c)   A description and an explanation to include:
     · opens parachute at C;
     · drag force increased/upward force increased;
     · lower terminal velocity;
plus 1 communication mark for using a suitable structure
and style of writing;                                                                                          4

(d) shows lower terminal velocity at D;
shows longer time to land; 2

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2. (a) force =350 N;
direction is upwards; 2

(b) acceleration = force/mass

= 350N /765kg

= 0.46 m/s2 ; 3

(c)   An explanation to include:
            acceleration decreases;
            resistive force increases;
            reducing the size of the unbalanced force;
plus 1 communication mark for ensuring that spelling, punctuation
and grammar are accurate, so that the meaning is clear                                    4

(d) An explanation to include:
mass / downwards force decreases;
causing an increase in acceleration; 2

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