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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