CAMBRIDGE IGCSE™ PHYSICS COURSEBOOK ANSWERS
Chapter 3
Questions
1
2
a
b
c
accelerate to right
slow down / accelerate to left
change direction
a
unbalanced; 20 N to left; accelerate
to left
balanced; no acceleration
unbalanced; 50 N downwards;
accelerate downwards
b
c
3
mass
weight
scalar
vector
unit = kg
unit = newton
measure of the
amount of matter
in a body; does not
change with positon
value depends
on local value of
acceleration due to
gravity
measured with a
(top-pan) balance
(measured with a
newton meter)
4
a
b
mass = 1 kg; weight is less than 10 N
mass = 1 kg; weight is greater than 10 N
5
a
i 686 N
ii 70 kg
iii 12.12 N
iv 5000 kg
v 7.69 × 10−3 m/s2
always the same
The force of gravity is much (15 033 times)
greater on Jupiter.
b
c
6
6
a
b
c
accelerating
weight greater than air resistance
The parachutist will slow down until
weight equals air resistance; and then fall
at constant speed.
7
Diagram should show a force acting towards
the centre of a circle that the bend is part of.
8
force of gravity
9
a
b
c
10 a
b
c
d
11 a
b
c
increases
increases
increases
500 N
1.6 m/s2
22 000 kg
0.15
23.53 N
23.52 N
same; weight is a force
12 66.7 m/s2
13 5.81 kgm/s
14 a
b
3 × 105 Ns
3 × 105 Ns
15 They both experience the same impulse (change
in momentum) but for the driver this takes
place over a longer interval of time, which
means that he experiences a smaller force.
p
16 a F = ___
t
b 2.4 × 104 N
c
980 N
d
24.5
e
240 N/kg
17 a
b
1.3 m/s
5 m/s; 36.9° east of south
Cambridge IGCSE™ Physics – Sang, Follows, Tarpey © Cambridge University Press 2021
CAMBRIDGE IGCSE™ PHYSICS COURSEBOOK ANSWERS
Exam-style questions
1
C;
[1]
2
C;
[1]
3
A;
[1]
4
C;
[1]
5
a
F = ma;
[1]
b
2.5 m/s2;
[1]
c
14 s;
[2]
d
Graph with time on the x-axis and speed
on the y-axis. [1] Straight line drawn from
(0, 0) through (14, 35);
[1]
e
245 m;
[1]
f
change direction;
[1]
a
p = mv;
[1]
b
1079 kg m/s;
[1]
c
7.35 × 103 N;
[2]
d
For a given change in momentum, seat
belts and the crumple zones increase
the time it takes for the car passengers
to come to a stop, [1] which reduces the
force on them. [1] In turn, this reduces the
potential injuries; [1]
6
7
Cambridge IGCSE™ Physics – Sang, Follows, Tarpey © Cambridge University Press 2021