questions on movement etc

1.  (a)  Mercury, Mars, Venus, Earth

  All four correct – 1 mark  1

    (b)  (i)  A calculation to include:

    1. (60 x 9.8 =) 588;
  2. N;    2

  (ii)  Mercury and Mars; (either order)  1

    (c)  An explanation to include:

    1. Venus; 2. it has the greatest atmospheric pressure; [Do not accept more than one answer]  2

(d)  An explanation to include:

  1. hotter;
2. other planets are colder the further from the Sun;
[Ignore explanations of why]  2

 2.  (a)  (i)  5 (N);  1

    (ii)  forces balanced / cancel / equal / book not moving /
no unbalanced force / no resultant force;  1

    (b)  (i)  air resistance / drag / air   friction;  1
  [ignore upthrust]

    (ii)  W – R / 5 – R  1

  3.  (a)  points plotted correctly;;  [Deduct 1   mark for each error]  2
  [Line not necessary]

    (b)  3 (m/s);  1

    (c)  (i)  acceleration = change in   velocity/ time taken;  1
  [Accept a = (v-u)/t]

  (ii)  acceleration = 3/15; [Allow ecf from part (b)]
    = 0.2 (m/s2);  2

4.  (a)  drag/resistance/force/push/thrust/upthrust;
  air/atmosphere; [Reject wind/friction]  2

  (b)  56;  1

    (c)  (i)  pull of Earth/weight/gravitational pull/downward (pull) greater than upward (push)/there is resultant force downwards; [Allow gravity]  1

  (ii)  both forces the same/ balanced/ equal/   resultant force is zero/ OWTTE;  1

  (d)  (i)  speed decreases; new lower terminal   velocity/horizontal region shown;   2

  (ii)  An explanation to include three from:

  air resistance increases; at start upward   force greater than downward force; eventually forces balance; larger surface area; air resistance decreases as parachutist slows down;  3

5.(a)  A calculation to include: =½ x1000 x 225;;
=  112 500 (J); [bald correct answer, 3 marks]
[If wrong answer look for:

  either½ x 1000 x152;
or  ½ x 1000 x 15;]  3

  (b)  A calculation to show:

Fs (work done) = change in KE = ½ mv2/OWTTE;

  F x 19   =   112 500;  [Allow ecf from part (i)]

  F = 5921 (nearly 6000 N);

  [bald correct answer – 1 mark]

5 (c)  An explanation to include four from:

  KE more than doubled;

  KE proportional to v2/= ½ mv2;

  braking distance more than doubled;

  depends on v2/KE;

  thinking distance doubled;

  constant braking force;  4

  (d)  An explanation to include:

  increase mass; KE increases;

  [Accept answer in terms of F = ma]   2

6.  (a)  0 – 2 (seconds);  1

  (b)    upwards;
  lift is slowing (even though it is   falling);  2
[Direction must be mentioned to score second marking point]

 7.  (i)  at a greater height;  1

  (ii)  work done = force(weight) x   distance   (height) (w = fd)  1

  (iii)  550 × 45 = 24750 J or 24.75 kJ     Accept joules/kilojoules
  Substitution = 1; Calc and unit = 1;   2

  (iv)  a= (v-u)/t 

Accept acceleration = change in velocity/time taken

     v = 3 × 10     = 30 m/s

  equation;  substitution; calculation and unit; 3

(v)  kinetic  1

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

  (b)  acceleration = force/mass = 350/765

  = 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 

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

Nuclear decay revision

Acceleration and Force Newton's Laws

Force calculations

Force

1.             A car of mass 1000 kg travelling at 10 m/s stops in 4 s        

Calculate     a) the average deceleration.

                                    b) the braking force.

2.         An aeroplane accelerates uniformly from rest (0 m/s) to 200 m/s in 40 s.

            What force does it exert on a pilot whose mass is 90 kg?

3.         The valve of a cylinder on an engine containing 12 kg of compressed gas is opened       and the cylinder empties in 1min 40 sec. If the gas leaves its chamber at 25 m/s       find.

            a)         the acceleration of the gas.

            b)         the force exerted on the chamber.

4.         A bullet of mass 20 g travelling with a velocity of 300 m/s hits an earth bank and is          brought to rest in 0.2 s.

            Find      a) the deceleration of the bullet.

                                     b) the force it exerts on the earth bank.

5.         A car hits a wall and decelerates at 40 m/s².  It exerts a force of 20 000 N on the wall.  What is the mass of the car?

6.         A stone of mass 0.5 kg falls into a sandpit exerting a force of 5N.  What is its     acceleration?

7.         A car of mass 750 kg stops uniformly in 5s.  If its initial velocity was 15 m/s calculate      the braking force.