True or False: [10]
a) Key is an arrangement of making or breaking a circuit.
b) A battery pushes the free electrons towards negative terminal.
c) Velocity is the distance travelled by a moving body per unit time.
d) A ball thrown by a boy from a roof top has oscillatory motion.
e) Electromagnetism means generation of electric field with application of magnet field.
f) A motion which repeats itself after a fixed interval of time is called periodic motion.
g) When an arrow is released from a bow, potential energy changes into kinetic energy.
h) Air conducts heat.
i) Displacement is a scalar quantity.
j) Primary cell is one which can be used again and again by recharging.
Answers
Answer:
SP1a Vectors and scalars
Student Book
7th 1 Sketch of jet ski with up and down
arrows, labelled upthrust and weight.
Up and down arrows of equal size.
5th 2 Mass measures the amount of material,
weight is a force; mass is a scalar
quantity, weight is a vector quantity;
mass is measured in kilograms, weight is
measured in newtons.
7th 3 It is a distance in a particular direction.
7th 4 Their displacement is zero, as they end up
at the same point from which they started.
7th 5 They are going around a bend, so their
direction is changing.
8th 6 The down arrow should be labelled
'weight', as 1000 N is a measurement
of force. The 'speed' label should read
velocity, as a direction is indicated as
well as the speed.
S1 Answers could include: 15 minutes is a time,
not a speed/velocity; unless she can walk in
a straight line from home to school, she is
referring to speed, not velocity.
S2 Displacement is a vector, and includes a
direction. Distance is a scalar. Any suitable
example, such as you could cover 3 miles in
distance during a walk but if you end up back at
your start point your final displacement is zero.
Speed is a scalar, velocity is a vector. Any
suitable example, such as a car travelling at 30
km/h on a winding road has a constant speed
but its velocity changes as it changes direction.
E1 Acceleration is a change in velocity with time.
Velocity includes direction as well as speed, so
if the direction of a vehicle is changing then its
velocity is changing, and so it is accelerating.
Exam-style question
a any from velocity, displacement,
acceleration, momentum (1)
b weight always acts downwards (1)
Activity and Assessment Pack
SP1a.1 Marble run
2 a The distance and displacement should be
the same.
b The distance should be larger than the
displacement. The displacement should be
the same as for path X.
4 This may depend on whether the curves in
path Y slow the marble down.
5 a The displacement is the same for both
paths, so the marble that took the shortest
time is the fastest.
b The marble travelled in a straight line
for X, so the direction did not change.
For path Y, the direction changed so the
velocity changes even if the speed does
not.
SP1a.2 Athletic event
2 Possible label placements are:
• distance the athletes will run – line drawn
from the starting blocks to the finish line,
following the curve of the track
• displacement of the runners at the end of
the race – straight line drawn from starting
blocks to finish line
• the athletes accelerate here. – near the
starting blocks and/or on the curve of the
track
• the runners have a constant speed here.
– any part of the track other than the initial
acceleration section
• the runners have a constant velocity here.
– on a straight part of the track
• the runners' velocity is changing here.
– near the starting blocks and/or on the
curve of the track
• distance the hammer travels during one
swing – distance marked around the circle
the hammer swings
• displacement of hammer after one swing
= 0 m – on the hammer
• weight = 400 N – force arrow shown
pointing down from hammer or box being
carried
• mass = 4 kg – on hammer or box being
carried.
SP1a.3 Vectors and scalars
Strengthen
1 a scalar
b vector
c scalar
d scalar
e vector
f scalar
g scalar
h vector
i vector