Page 81 - Physics

Introduction to force
(vi) It is fact that any object always
has mass but does not always have
weight. What must be present and
acting on the mass for it to have
weight?
(a) an acceleration due to gravity
(b) a set of scales for measurement
(c) displaced water in a beaker
(d) friction due to air resistance
(vii) The balls in Figure 3.22 have the same
size. Which one will hit the ground
fi rst if they are dropped at the same
time and at the same height?
Wooden ball Plastic ball Metal ball
Figure 3.22
(a) metal fi rst, then wood, then
plastic last.
(b) wood fi rst, then plastic, then
metal last.
(c) they will all hit at the same time.
(d) there is no way to tell.
(viii) A falling object is pulled down by
the earth. The earth is pulled up
towards the object. Why doesn’t the
earth move?
(a) Because the earth has only
gravity.
(b) Because the earth has a
very large mass and a small
acceleration.
(c) Because the earth has a
very small mass and a large
acceleration.
(d) Because air resistance gets in
the way.
Physics Form 1 Final.indd 75
2. Match item in column A with its
corresponding item in column B.
Then, write the letter of the correct
response in the provided space.
Column A Answer Column B
(i) Stretching A. effect of magnet
on iron material
(ii) Attraction B. force in string
(iii) Friction C. extension of rigid
material such as
spring
(iv) Viscosity D. two rough surfaces
(v) Tension in contact
E. resistance to
motion in fl uid
Section B
3. (a) The force of friction between the
surface of a fl oor and the surface
of a box in contact with the fl oor
is 200 N. We wish to move the
box on the fl oor with constant
velocity. How much force has
to be applied on the box?
(b) If a box has a mass of 80kg.
Calculate the coeffi cient of
friction?
4. (a) A student conducts an
experiment to compare the
weight of an object on Earth
and the Moon. They fi nd that
the object’s weight is six times
less on the Moon compared to
Earth. Explain the difference in
weight and why it changes on
the Moon.
(b) If an object has a mass of 200 g
on the earth, how much would
it weigh on the moon given that
the acceleration due to gravity
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