Physics Form 4 Page 1 of 9 Half-Yearly T3/2016-2017

Answer ALL questions showing your working

Where necessary give your answers correct to 2 decimal places.

Table of Formulae

Acceleration due to gravity g = 10 m/s² Average speed = total distance v = u + at a = (v – u) total time t s = ut + ½at2 s = (u + v)t v2 = u2 + 2as 2 Refractive index n = real depth Refractive index n = speed of light in air apparent depth speed of light in other medium Magnification = height of image = image distance from lens height of object object distance from lens Speed of wave v = fλ Periodic time T = 1 f Area of a triangle = ½bh Area of a trapezium = h(a + b) 2

For examiners’ use only

GIRLS ’ SECON DARY , MRIEHEL

HALF YEARLY EXAMINATIONS

2016/2017

FORM: 4 PHYSICS Time: 1½ hrs

Name:________________________________ Class:___________

Question 1 2 3 4 5 6 7 8 Theory Practical Total

Max. Mark 8 8 8 8 8 15 15 15 85 15 100

Score

Track 3

Physics Form 4 Page 2 of 9 Half-Yearly T3/2016-2017

SECTION A – This section carries 40 marks

1. This question is about optics

a) The diagram shows a ray of light incident onto a plane

mirror AB.

i) OX is the ____________________ ray while OY is

the _________________________ray. [1]

ii) Find the angle of incidence i. [1]

_____________________________________________

iii) What is the angle of reflection r? __________________ [1]

iv) Tamara wrote some notes from her observations, some of which are wrong.

Identify which statements are true and which are false. [3]

Statement True/False

i) If the angle of incidence is 45⁰, the angle of reflection

should be double the size. __________

ii) The normal should be drawn at 90⁰ to the plane mirror. __________

iii) Reflection occurs when waves pass from one medium to another. __________

b. Complete the following diagram

showing the refracted and

emergent rays. [2]

2. This question is about the equations of motion.

A van travelling with an initial velocity of 72 km/h

skids to a stop, moving a distance of 25 m.

a) Find the initial velocity of the van in m/s. [2]

b) What is the final velocity of the van? [1]

incident ray

air

air

glass

A B 55

i r

X Y

N

O

Physics Form 4 Page 3 of 9 Half-Yearly T3/2016-2017

c) Calculate the deceleration of the van. [3]

d) Find the time it takes to stop. [2]

3. This question is about motion

Ruth decides to use the apparatus shown in

the diagram to find a value for the acceleration

due to gravity “g”.

a) She uses a particular method to find the value of g.

Indicate the order of numbers 2 to 4 in which the

steps of the experiment have to be performed. [3]

Ruth then proceeds to do the experiment.

b) The initial speed of the ball bearing is ______________________________________ [1]

c) Ruth uses a ___________________________to measure the height fallen by the metal ball. [1]

d) She then decides to repeat the experiment using a heavier metal ball together with a stopwatch to

measure the time taken by the ball to fall.

i) Does a heavier metal ball make a difference in the measured value of “g”? Why? [2]

ii) Using a stopwatch instead of the electronic timer is not such a good idea. Why? [1]

The apparatus was set up as shown. 1

The digital timer stops as the metal ball passes in front of the photodiode.

The metal ball is attached to the electromagnet.

As the switch is closed, the metal ball falls and the electronic timer starts.

Ball bearing

Electromagnet

Photodiode

Pad

stand

Physics Form 4 Page 4 of 9 Half-Yearly T3/2016-2017

4. This question is about optics

During a Physics lesson, John and Maria were supplied with an optical bench as shown in the diagram.

a) Which distance, X or Y represents the:

(i) object distance, ____________ [1]

(ii) image distance ____________ [1]

b) The two students use a convex lens having a focal length of 2 cm. They vary the object

distance u and measure the corresponding image distance v.

The table shows the reading obtained by the students and the corresponding magnification

m in each case.

Object distance u/cm 2.8 3.0 3.3 4.0 4.5 6.0 12.0

Image distance v/cm 7.0 6.0 5.1 4.0 3.6 3.0 2.4

Magnification m 2.50 2.00 1.55 _____ 0.80 ____ 0.20

c) Fill in the two missing numbers in the table. [2]

d) Plot a graph of magnification m on the y-axis against the image distance v on the x-axis.

Draw the best straight line through the points. [4]

5. This question is about velocity time graphs.

A car is travelling at 25 m/s.

The driver realises that he

has to decelerate immediately

and stop the car as a pedestrian

was going to cross the road.

The driver applies the brakes

and stops the car.

a. On the graph, label the

part AB where the driver

is driving at constant

speed. [1]

object image

Light source

X Y

convex lens

0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0

30

25

20

15

10

5

0

Physics Form 4 Page 5 of 9 Half-Yearly T3/2016-2017

b. Using the graph, calculate the thinking distance travelled by the car. [2]

c. Find the deceleration of the car. [2]

d. Using the graph, find the braking distance of the car. [2]

e. Hence find the total stopping distance of the car. [1]

SECTION B – This section carries 45 marks

6. This question is about Waves

a. Label diagrams 1 and 2 with the appropriate words given in box below:

[3]

Diagram 1

Diagram 2

From the above diagrams, answer the following questions:

b. Which of the diagrams represent a transverse wave? ______________________________ [1]

c. Which of the diagrams represent a longitudinal wave? ______________________________ [1]

d. Mention two differences between transverse and longitudinal waves. [2]

wavelength amplitude crest

trough compression rarefaction

Physics Form 4 Page 6 of 9 Half-Yearly T3/2016-2017

e. Look carefully at the diagram below and answer the following questions:

i. Write down the periodic time of the wave. _____________________________ [1]

ii. Calculate the frequency of the wave. [1]

iii. If the speed of the wave is 330 m/s, calculate the wavelength of the wave. [2]

iv. Fill in the missing words in the following table: [2]

Gamma

Rays _________ _________ _________

Infra Red

Rays _________ Radiowaves

f. Ultrasound waves have a very high frequency beyond

human hearing range. However, these sounds are very

much used by animals such as bats and dolphins.

Humans too make use of these sounds when studying

the seabed or to track any sunken vessels.

The diagram shows a vessel using the echo sounder

to determine the depth of the sea.

If a pulse was sent to the seabed and took 20 s to return

back, calculate the depth of the sea if the speed of sound

in water is 343.2 m/s. [2]

Physics Form 4 Page 7 of 9 Half-Yearly T3/2016-2017

45° 45° object

45°

45°

A

B

white light

screen

7. This question is about light waves.

(a) Mia shines a ray of light on a 60°-60°-60° glass prism. She wants to investigate what happens

when white light passes through this prism.

i. Complete the diagram to show how the red and the violet colours are produced on the

screen. Write R for red and V for violet at the place where these colours would be seen. [3]

ii. Which one of these two colours is the least refracted? Explain why. [2]

(b) Mia then investigates how a periscope works. This periscope consists of two 45°-90°-45° glass

prisms. The critical angle of glass is 42°.

i. Name the effect taking place at points A and B. [1]

ii. Write down the two conditions for this effect to take place. [2]

Physics Form 4 Page 8 of 9 Half-Yearly T3/2016-2017

(c) Mia then experiments with a convex lens. She placed an object 1 cm high 5 cm in front of the

lens. The lens has a focal length of 3 cm. Note: 1 square represents 1 cm.

i. Complete the ray diagram showing how the image of the object is produced. [3]

ii. Write down two characteristics of the image formed. [2]

iii. Measure the image distance. ______________________________________________ [1]

iv. Give one use for such a lens. ______________________________________________ [1]

8. This question is about Freefall

Sarah drops a piece of plasticine of mass 135 grams from a height of 8 m above the ground.

a. Draw the two forces acting on the plasticine as it is falling to the ground. [2]

b. What is the initial velocity of the stone? _______________________________________ [1]

c. What is the mass of the plasticine in kg? [1]

d. What is the initial acceleration of the plasticine as it falls to the ground? ______________ [1]

e. What is this acceleration called? _______________________________________________ [1]

f. Calculate the time taken for the plasticine to reach the ground. (ignore air resistance) [3]

F F

O

plasticine

Physics Form 4 Page 9 of 9 Half-Yearly T3/2016-2017

g. Find the velocity just before the plasticine hits the ground. (ignore air resistance) [2]

h. Sarah decides to attach a small parachute to the piece of plasticine. Explain any change in the

time taken to reach the ground? [2]

i. Sarah repeats the experiment using a piece of plasticine of mass 350 grams. Assuming that no

opposing forces act in both cases, explain any difference, if any, would there be in the final

velocity of the larger piece of plasticine. [2]

END OF PAPER

PLEASE CHECK YOUR WORK!