Paper 2 / section b

Suggested answer

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

1

The depth of sinking increases, pressure increases

As the area of contact increases, the pressure exerted decreases

5

Section B Problem Solving Qualitative (Question 9)

9 (b)

1

1

1

1

The fan blows /remove/push/force air out the vents

Produce a partial vacuum area in the vacuum cleaner/low pressure

Atmospheric pressure is higher than the pressure inside the vacuum cleaner/Difference in pressure

Push the dirt into the vacuum

4

Question 9

Suggestion Rationale

1Type of fluid

Oil

2 Incompressible/ No air bubble/Cannot be compress/water produce air bubble

 Any 5 correct

3 Characteristic of fluid

High boiling point/ Low density/ High viscosity

4 Does not change to gases state easily/lighter/Less friction/Does not evaporate easily

5 Size of the master piston

Small

6 To produce high pressure/small force used

7 Size of slave piston

Big

8 To produce a big force on the disc/ Force is directly proportional to area

9Material for fluid transmission pipe

Plastic/ Aluminium / Steel

10 Strong/ Does not break easily/Does not rust easily/ Non corrosive/withstand temperature/prevent leakage

TOTAL 10

9 (c)

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

1

1

1

Heat flows from hot water to thermometer

Achieve thermal equilibrium

Temperature of water is the same as temperature shown by thermometer

No more heat flows at 100 oC

4

Section C (Decision Making Skill) ( Section C: 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

Question 11

11 (c)

Characteristics Explanation

Hollow plastic stopper Bad conductor of heat /Reduce heat loss/bad conductor/good insulator/reduce heat escape to the surrounding/Trapped air

Space X is vacuum Prevent heat lost from the sides through convection/heat cannot travel through vaccum

Double walled tube made of glass

High specific heat capacity/

Becomes hot very slowly

Double walled tube coated by shiny paint

Reflect heat from the wall of 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

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

1

1

When I increases, V increases

The resistance increases

Because temperature increases

(iii) 1 Decrease

Section C (Decision Making Skill) ( Section C: Question 12 )

12 (c)

Characteristics Explanation

Shape of filament wire

Coiled

So that a very long wire can be fitted inside the glass bulb to give out a bright light /

High resistanceThickness of the filament wire

Thin

To give more resistance per unit length/

More heat Type of wire

Tungsten

Has high melting point/

Does not break easily

Pressure in the bulb

Low pressure

The bulb will not burst/explode after for a long time

The most suitable is R Because

Coiled , thin wire, nitrogen at low pressure

11(d

)(i)

1

1

Correct substitution

I= P/V

= 11/240

=0.046 A/ 0.05 A

(ii) 1 Heat loss= 11J -10 J=1J

(III)

1

1

Efficiency = Power output x 100%

Power input

= 10 x 100%

11

= 90.91%

5

Question 12 (d)