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Physics · Oct / Nov 2020 · Paper 42 · Question 1

0625

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The question as text

A sky-diver jumps out of a hot-air balloon, which is 4000 m above the ground. At time = 30 s, she opens her parachute. Fig. 1.1 is the speed-time graph of her fall. 60 40 speed m / s time / s 20 0 0 10 4.0 20 30 40 50 Fig. 1.1

Read automatically from the paper; the printed page above is exact.

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  • 1(a)(i)[1]

    X near (30,60)

  • 1(a)(ii)[1]

    Y AND Z near any horizontal section of graph

  • 1(b)[4]

    any two from:

    weight OR force of / due to gravity acts down
    (force of / due to) air resistance / drag / friction acts up / opposes motion
    initially / up to 10 s: resultant force is downward OR downward force is greater than upward force
    resultant force causes acceleration
    air resistance increases as speed increases / she accelerates

    any two from:

    acceleration (down) initially / for first 10 s
    acceleration decreases as air resistance increases / resultant force decreases
    zero acceleration / constant speed / terminal velocity reached when upwards force = downwards force OR when no / zero resultant OR when forces balanced OR when downward force = air resistance
    terminal velocity / constant speed reached after (about) 10 s OR at 60 m / s

  • 1(c)[2]

    (average speed =) {initial speed + final speed} / 2 words, symbols or numbers

    OR (average speed =) distance (from area) / time words, symbols or numbers

    (average speed = 40 / 2 =) 20 m / s

    OR (av speed = 80 / 4 = ) 20 m / s

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