ST VENERA BOYS’ SECONDARY SCHOOL HALF …stc.veneraboys.skola.edu.mt/Exam Papers/Form 3/F3 Physics...

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ST VENERA BOYS’ SECONDARY SCHOOL

HALF-YEARLY EXAMINATIONS 2014-15

Form 3 Physics (Track 3) Time: 1hr 30mins

Name: _____________________________ Class: ___________

Answer ALL questions in Section A and Section B.

All working must be shown. The use of a calculator is allowed.

Where necessary, take the gravitational field strength on Earth as g = 10N/kg.

Useful Equations:

Density ρ =

Weight W = m × g

Moments M = Force × perpendicular distance

Pressure P = P = h × ρ × g

For examiner’s use:

1

(10)

2

(10)

3

(16)

4

(4)

5

(15)

6

(15)

7

(15)

Main

(85)

Practical

(15)

Total

(100)

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SECTION A

Answer all questions in this section. This section carries 40 marks.

1. Complete the following sentences by writing the name of the instrument used and

the S.I unit.

(1 mark each – 10 marks)

a.

i) The ____________________ is used to measure the length of the

table.

ii) The standard units are ____________.

b.

i) The ____________________ is used to measure the time to run

across the yard.


c.

i) The ____________________ is used to measure the mass of an

empty beaker.


d. i) The ____________________ is used to measure the volume of

some oil.

ii) The standard units are ____________________.

e.

i) The ____________________ is used to measure the weight of a

body.

ii) The standard units are ____________________.

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2. The diagram below shows the forces acting on an aeroplane flying at a constant

height.

a. What are the forces labelled G and H?

_______________________________________________________________________________

_____________________________________________________________________(2 marks)

b. Force G is equal to 40000 N. The horizontal resultant force is zero. What is the size

of the thrust force?

__________________________________________ (1 mark)

c. The aeroplane now needs to accelerate forward. What can be said about the

sizes of the thrust force and force G? (Underline the correct answer.)

The thrust force is greater than force G.

The thrust force is equal to force G.

The thrust force is smaller than force G. (1 mark)

d. The aeroplane has a mass of 80,000 kg. What is its weight in Newtons?

_______________________________________________________________________________

_______________________________________________________________________________

_____________________________________________________________________(2 marks)

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e. The aeroplane is travelling at constant height. What can be said about the size of

the lift force and force H? (Underline the correct answer.)

The lift force is greater than force H.

The lift force is equal to force H.

The lift force is smaller than force H. (1 mark)

f. Suggest a suitable value for the lift force if the aeroplane needs to go higher.

__________________________________________ (1 mark)

g. Is force a scalar or a vector quantity? Explain.

_____________________________________________________________________(2 marks)

3. Ms Caruana works in a school. She received a new chair for her class.

The chair has a mass of 36kg.

a. What is the weight of the chair?

______________________________________________________________________________________

____________________________________________________________________________(2 marks)

b. The chair rests on four legs. Each leg has an area of 0.01m by 0.01m. Calculate

the total are in contact with the floor.

_______________________________________________________________________________

_____________________________________________________________________(3 marks)

c. Calculate the pressure the chair exerts on the floor.

_______________________________________________________________________________

_____________________________________________________________________(2 marks)

d. To decorate her classroom, Ms Caruana buys a new aquarium. Given that the

water in the aquarium is 0.5m high and the density of water is 1000kg/m3, what is

the pressure at the bottom of the aquarium?

_______________________________________________________________________________

_____________________________________________________________________(3 marks)

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e. A hydraulic press was given to the school where Ms Caruana works, so that waste

paper could be compressed into bundles.

i. If a force of 30N is applied to Piston A, calculate the pressure in the oil at A.

_________________________________________________________________________

________________________________________________________________(2 marks)

ii. What is the pressure exerted by the oil at B.

_____________________________ (1 mark)

iii. Calculate the upward force acting on the large Piston.

_________________________________________________________________________

________________________________________________________________(3 marks)

4. Look at the sentences below. Fill in the missing words.

a. A body behaves as if its whole weight were concentrated at one point. This point

is called the ________________________. (1 mark)

b. A sports car tends to have a ___________ centre of gravity. As a result, they are

more ____________. (2 marks)

c. The centre of gravity of a cruise ship shifts ____________ as passengers move from

the lower to the upper decks. (1 mark)

30N

Piston A

Piston B

Compressed

waste paper

bundles

Area = 0.0007m2 Area = 0.36m2

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SECTION B

Answer all questions in this section. This section carries 45 marks.

5. This question is about the extension of a spiral spring.

The table shows the results obtained when different stretching forces (F) are applied

to a spiral spring causing it to stretch.

Stretching Force (N) 0 2 4 6 8 9

Extension (mm) 0 4 12 16 20

a. Complete the missing data in the table. (1 mark)

b. Plot a graph of the stretching force (x-axis) against the extension (y-axis) on the

graph paper provided. (7 marks)

c. From the graph:

i. A stretching force of _________ N produces an extension of 6mm. (1 mark)

ii. A force of 5N produces an extension of _________mm. (1 mark)

iii. The greatest load which can be loaded on this spring without damaging it

is _________N. This is referred to as the ______________ limit of the spring.

Mark this point with a letter E on your graph. (3 marks)

d. What can you conclude from your graph? Why? (2 marks)

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

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6. This question is about moments.

a. The figure below shows a heavy rock weighing 800 N. A man tries to lift the rock

by means of a solid iron lever, 2 metres long. The lever is pivoted at 40 cm from

the centre of the rock.

i. Mark the weight of the rock by means of an arrow and label it 800 N.

(1 mark)

ii. How far is the downward force, F, from the pivot? (2 marks)

_________________________________________________________________________

iii. Use the principle of moments to calculate how much force must the man

use in order to just lift the rock. (4 marks)

_________________________________________________________________________

_________________________________________________________________________

_________________________________________________________________________

_________________________________________________________________________

_________________________________________________________________________

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b. The diagram below shows a uniform ruler balanced on a fulcrum with a weight of

1.5 N hanging from one end.

i. What name is given to the point A? (1 mark)

_________________________________________________________________________

ii. Add to the diagram an arrow to show the force of attraction of the Earth on

the rule. Label this arrow B. (1 mark)

iii. By what name is this force more commonly known? (1 mark)

_________________________________________________________________________

iv. By using moments, calculate the mass of the ruler. (5 marks)

_________________________________________________________________________

_________________________________________________________________________

_________________________________________________________________________

_________________________________________________________________________

_________________________________________________________________________

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7. This question is about density.

a. Solve the same problem as Archimedes using the information given here.

A B C

Mass in grams 3800 3800 3800

Volume in cm3 380 200 300

The density of gold is 19 g/cm3

The density of silver is 10 g/cm3

Decide which trophy is gold, which is silver and which is a mixture by finding the

density of each cup. Give an explanation for your answer. (4 marks)

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

____________________________________________________________________________

b. Daniel wanted to find the density of lemonade. What instrument should he use to

measure:

i. the volume of the lemonade? ___________________________ (1 mark)

ii. the mass of the lemonade? _____________________________ (1 mark)

c. Explain how he can find the volume, mass and density of the lemonade.

Volume of the lemonade. (2 marks)

____________________________________________________________________________

____________________________________________________________________________

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Mass of the lemonade. (3 marks)

____________________________________________________________________________

____________________________________________________________________________

____________________________________________________________________________

____________________________________________________________________________

____________________________________________________________________________

Density of the lemonade. (1 mark)

_________________________________________________________________________

d. Daniel observed the upward flow of the gas bubbles in the lemonade. Explain this

flow. (2 marks)

_______________________________________________________________________________

_____________________________________________________________________________

e. Daniel fills a measuring cylinder with 55cm3 of lemonade. When he

puts some ice flakes in the lemonade, the total level rises to 85cm3.

Determine the volume of the ice inside the cylinder.

(1 mark)

_______________________________________________________________________________

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