Transcript Skema P2b jawapan physics ppd (Zalipah)

Paper 2 / section b
Suggested answer
Section B Problem Solving Qualitative (Question 9)
9
(a)
(i)
1
Pressure is defined as force per unit area
P=F/A, where F= force, A=area
(ii)
1
1
1
Depth of singking in Diagram 9.1 is deeper than in
Diagram 9.2
The weight/load of the man in Diagram 9.2 and
Diagram 9.1 is equal
Area of contact with the sand in Diagram 9.2 is
larger than in Diagram 9.1
(iii)
1
The depth of sinking increases, pressure increases
1
As the area of contact increases, the pressure
exerted decreases
5
Question 9
9
(b)
1
The fan blows /remove/push/force air out the
vents
1
Produce a partial vacuum area in the vacuum
cleaner/low pressure
1
Atmospheric pressure is higher than the pressure
inside the vacuum cleaner/Difference in pressure
1
4
Push the dirt into the vacuum
9 (c)
Suggestion
1
Type of fluid
Rationale
2
Oil
3
Characteristic of fluid
4
High boiling point/ Low
density/ High viscosity
5
Size of the master piston
6
Small
7
Size of slave piston
Material for fluid
transmission pipe
Plastic/ Aluminium / Steel
Any 5
correct
Does not change to gases state
easily/lighter/Less
friction/Does not evaporate
easily
To produce high pressure/small
force used
8
To produce a big force on the
disc/ Force is directly
proportional to area
10
Strong/ Does not break
easily/Does not rust easily/
Non corrosive/withstand
temperature/prevent leakage
TOTAL
Big
9
Incompressible/ No air
bubble/Cannot be
compress/water produce air
bubble
10
Section C (Decision Making Skill) ( Section C: Question 11 )
11 (a)
(i)
1
Two bodies are said to be in thermal equilibrium
when
Both bodies are at the same temperature/ The net
heat flow between the two bodies is zero/
There is no net heat flow between them
(ii)
1
Heat flows from hot water to thermometer
1
Achieve thermal equilibrium
1
Temperature of water is the same as temperature
shown by thermometer
1
No more heat flows at 100 oC
4
Question 11
11 (b)
1
1
1
1
Heat released by M = Heat absorbed by water
Substitution:
(0.5) (800)(100-T)= (0.2)(4200)(T-30)
T= 52.58 oC
Note: no e.c.f
4
(ii)
1
No heat is lost to the surrounding
11 (c)
Characteristics
Hollow plastic stopper
Space X is vacuum
Double walled tube made of glass
Explanation
Bad conductor of heat /Reduce
heat loss/bad conductor/good
insulator/reduce heat escape to
the surrounding/Trapped air
Prevent heat lost from the sides
through convection/heat cannot
travel through vaccum
High specific heat capacity/
Becomes hot very slowly
Double walled tube coated by shiny Reflect heat from the wall of
paint
thermos flask/not absorb heat
The most suitable is W
Because
Hollow plastic stopper, space X
is vacuum, double walled tube
made of glass and coated by
shiny paint
Section C (Decision Making Skill) ( Section C: Question 12 )
12 (a) (i)
1
Work done in moving one coulomb of charge from
one point to another /
Energy dissipated per unit charge by the resistor /
V= E/Q, E= work done, Q= quantity of charge
(b) (ii)
1
When I increases, V increases
1
The resistance increases
1
(iii)
1
Because temperature increases
Decrease
12 (c)
Characteristics
Shape of filament wire
Coiled
Thickness of the filament wire
Thin
Explanation
So that a very long wire can be
fitted inside the glass bulb to
give out a bright light /
High resistance
To give more resistance per unit
length/
Type of wire
More heat
Has high melting point/
Tungsten
Does not break easily
Pressure in the bulb
The bulb will not burst/explode
after for a long time
Low pressure
The most suitable is R
Because
Coiled , thin wire, nitrogen at
low pressure
Question 12 (d)
11 (d) (i)
Correct substitution
1
I= P/V
= 11/240
1
(ii)
1
=0.046 A/ 0.05 A
Heat loss= 11J -10 J=1J
Efficiency = Power output x 100%
(III)
Power input
1
= 10 x 100%
11
1
5
= 90.91%