This document contains the answers to a physics exam for Form 4 students in Malaysia. Part 1 discusses forces, pressure, and Pascal's principle. Part 2 covers buoyant force and Archimedes' principle, calculating buoyant forces on different objects. Part 3 provides modifications and explanations for improving the design of a hot air balloon.

1. Jawapan fizik ujian selaras ogos 2014 (form 4)
1 (a) Force is action on an object that can result in changes
like size, shape and direction.
(b) 1. surface area A1 is smallerr than A2
2. forces F1 is smaller than F2
3. pressure P1 is equal to P2
4. when surface area is larger, the force exerted on the
piston will increase.
5. Pascal’s principle
(c) 1. Function- to transfer water from beaker to cylinder.
2. The pressure at lowest point in cylinder is greater
than the atmospheric pressure, the liquid flows out
at lowest point in cylinder/at the end of rubber tube
in cylinder.
3. The pressure in the rubber tube decreases as the
water flows out and a partial vacuum is created.
4. The higher atmospheric pressure water into the
tube.The water flows until the liquid surface in
cylinder reaches the same level as in beaker.
(d)
Modification/
suggestion
Explanation
Oil Incompressible/
No air bubble
High boiling point/
Low density/
High viscosity
Does not change to gas state easily/
Does not evaporate easily
Lighter/
Fluid does not flow easily
Small master
piston
High pressure produced with a small force
Big slave piston Produce bigger output force
Aluminium/
Steel
Strong/
Does not break easily/
Non corrosive/
Does not rust easily
1
5
4
10
TOTAL MARKS 20

2. 2 (a) Buoyant force is an upward force acting on an object which has
displaced some fluid in which it is immersed.
Daya apungan adalah daya tujah bertindak ke atas objek yang
disesarkan oleh cecair yang mana ia tenggelam.
1
(b)(i) 1. Buoyant force are produced by the water to act on the rods
2. The buoyant force are able to balance/support the weights of the
rods.
2
(ii) Archimedes’ Principle
Prinsip Archimedes
1
(c)(i) Rod Q has displaced more water
Rod Q mempunyai lebih banyak air yang tersesar
1
(ii) Buoyant force acting on Rod Q > Rod P
Daya apungan bertindak di Rod Q > Rod P
1
(iii) Rod Q 1
(d)(i) Weight of water displaced = 1 000 (5) ( 10)
= 50 000 N
2
(ii) Weight of cargo = 50 000 – 250 (10)
= 47 500 N
1
(e)
Suggestion Explanation
Material – Extra
strong
To ensure the balloon does not burst or
leak easily and the people in a strong
basket will be safer.
Power-Strong It can heat up the air faster and the
balloon can ascennd faster
The holding cable-
Light and strong
It will decrease the overall weight of the
balloon in place safely
Balloon should pulled
down by motor
So that the balloon can descend faster
and more safety without human error and
fatique
Most Suitable is
balloon X
Its balloon and basket materials are
strong, it has a strong burner, its holding
cable is strong and light and its descend is
operated by motor.
10
TOTAL MARKS 20