Download PROPERTIES OF MATTER Question 1 (8 marks) Two metal balls

UNIVERSITY OF KWAZULU-NATAL
SECOND SEMESTER EXAMINATION: 12th November 2009
Subject, Course and Code: Physics Foundation PHYS099 and PHYS199
DURATION: 3 HOURS
Student number: __________________________________
TOTAL MARKS:180
Seat number: _______________
INTERNAL EXAMINERS:
Ms B. Adams, Ms W. Dlamini, Mrs S. Halstead, Mr R. Webber, Mr E Zhandire
EXTERNAL EXAMINER Dr V Couling
ANSWER ALL QUESTIONS ON THIS PAPER.
IN THEIR OWN INTERESTS STUDENTS ARE REQUESTED TO WRITE LEGIBLY.
THIS PAPER CONSISTS OF 15 PAGES. PLEASE SEE THAT YOU HAVE THEM ALL.
PROPERTIES OF MATTER
Question 1 (8 marks)
Two metal balls are placed on an equal arm balance as
shown on the right. The volume of Y is 80 cm3 while the
volume of Z is 10 cm3. The balance was previously
zeroed correctly.
Y
Z
(a) Compare the properties of mass and density of the
balls. Explain your reasoning.
(4)
(b) Now imagine that Z is removed. Then another ball, which is exactly the same as Y, was
made into eight small balls. These small balls were all placed on the right hand side, with Y
still on the left. What will happen to the balance? Describe how the balance will end up.
Give a brief explanation.
(4)
UNIVERSITY OF KWAZULU-NATAL
th
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
12 November 2009
MECHANICS
Question 2:
(10 marks)
North
Thuli walks from her house (A) to the shops (B) and then to her friend’s
house (C). Together they go to school (D), as shown alongside.
The displacement of B from A ( AB ) is 500 m north.
The displacement of C from B ( BC ) is 600 m on a bearing of 130o.
The displacement of D from C ( CD ) is 300 m west.
B 130.0o
500 m
600 m
D
Use the given reference frame and show diagrams when necessary.
C
300 m
A
North +
(a) What distance did Thuli walk to school on that day?
(b) Use components to find the displacement of school from home ( AD )
(1)
East +
(8)
(c) If Thuli walks directly home from school at the end of the day, how far does she walk?
(1)
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UNIVERSITY OF KWAZULU-NATAL
Question 3
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
th
12 November 2009
(9 marks)
The following velocity-time graph shows the motion of an object with an initial position of
xo = 15 m.
(a) Find the position of the object at 6 s.
Show your calculations.
(b) Sketch an acceleration-time graph for the above motion on the axes below.
a (m/s2)
t (s)
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(6)
(3)
UNIVERSITY OF KWAZULU-NATAL
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
th
12 November 2009
Question 4
(7 marks)
A zebra first sees a lion when the lion is 12.5 m away and moving towards the zebra with a
velocity of 5 ms-1. The zebra begins to accelerate away from the lion; at the same time the lion
accelerates towards the zebra at 2 ms-2.
(a) If the lion takes 15 seconds to catch the zebra, how far does the zebra travel before it is
caught?
(4)
(b) What is the zebra’s acceleration, if it’s moving at 38 ms-1 when the lion catches it?
(3)
Question 5 (7 marks)
Take the magnitude of acceleration due to gravity as 9.8 ms-2.
Show the reference frame that you use.
A soccer player kicks a ball straight up with an initial velocity of 15 ms-1.
(a) What is the maximum height reached by the ball?
(4)
(b) How long does it take the ball to come back to the ground?
(3)
Page 4 of 15
UNIVERSITY OF KWAZULU-NATAL
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
Question 6 (6 marks)
A force of 210 N acts on a block at an angle of
20.0° to the horizontal along a frictionless surface.
With the block initially at rest, it moves over a
horizontal displacement of 4.50 m.
th
12 November 2009
210 N
20.0 kg
20.0º
Determine:
(a) The magnitude of acceleration of the block, and
(3)
(b) Its final velocity
(3)
Question 7
(7 marks) Take the magnitude of acceleration due to gravity as 9.8 ms-2
A bag of sugar weighs 24.5 N on Earth and is taken to the Moon where the acceleration due to
gravity is 16 that on the Earth. Explain your reasoning for the following questions.
Take the magnitude of acceleration due to gravity on Earth as 9.8 ms-2
(a)
What is the mass of the sugar bag on the moon?
(2)
(b)
What is the weight of the sugar bag on the Moon?
(5)
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UNIVERSITY OF KWAZULU-NATAL
Question 8
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
th
12 November 2009
(17 marks) Take the magnitude of acceleration due to gravity as 9.8 ms-2
A man is mowing the grass with a lawnmower of mass 200 kg. He pushes down on the
lawnmower with a force of 350 N at an angle of 70o to the horizontal as shown below. The
frictional force acting on the lawnmower is 100N.
350 N
(a) Draw a freebody diagram showing all the forces acting on the
lawnmower.
(4)
70E
(b) Find the normal force from the ground on the lawnmower.
(4)
(c) Does the normal force increase, decrease or stay the same as the angle 70o is increased?
Explain in terms of components.
(3)
(d) Find the acceleration of the lawnmower.
Page 6 of 15
(6)
UNIVERSITY OF KWAZULU-NATAL
th
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
12 November 2009
ELECTROSTATICS (29 marks)
NOTE: Take the electrostatic constant in air to be k = 9.00 x 109 Nm2C-2.
Q1= -4.00 FC
Question 9 (20 marks)
Using the diagram shown on the right:
(a) Calculate the electrostatic force exerted by Q1 on Q2
N
20.0 mm
40.0 mm
Q3= +8.00 FC
Q2= -1.00 FC
(5)
(b) By proportional reasoning, determine the electrostatic force exerted by Q3 on Q2
(4)
(c) Use a vector diagram to determine the resultant electrostatic force on Q2
(6)
(d) Determine the resultant electric field due to Q1 and Q3 at the point occupied by Q2
(5)
Page 7 of 15
UNIVERSITY OF KWAZULU-NATAL
th
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
Question 10 (9 Marks)
The diagram shows three equally spaced charges of magnitude 4 nC.
(a) What is the direction of the resultant electrostatic force on:
i) Charge S
12 November 2009
-4nC S
North
600
V
0
60
+4nC T
600
U +4nC
ii) Charge T
(5)
(b) What is the direction of the resultant electric field at point V, which is an equal distance
from all the charges.
(4)
Page 8 of 15
UNIVERSITY OF KWAZULU-NATAL
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
th
12 November 2009
ELECTRIC CIRCUITS
Question 11 (10 marks)
In the circuit below, there are three identical resistors, and bulbs A and B are identical. Initially
both bulbs are glowing. Neglect internal resistance of the cell?
A
B
(a)
If bulb A is removed from its socket, what happens to bulb B? Explain your reasoning.
(3)
(b) If bulb A is put back and bulb B is now removed, what happens to bulb A? Explain your
reasoning.
(3)
(c) The circuit is restored to its initial condition. A conducting wire of negligible resistance is
then connected between points1 and 2. What happens to the brightness of each bulb?
Explain your reasoning.
(4)
Page 9 of 15
UNIVERSITY OF KWAZULU-NATAL
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
th
12 November 2009
Question 12 (13 marks)
The following questions refer to the circuit diagram below. Neglect internal resistance of the
battery.
10.0 Ω
8.0 Ω
6.0 Ω
3.0 Ω
ε = 30 V
Calculate:
(a)
the total external resistance of the circuit.
(4)
(b)
the current through the battery.
(3)
(c)
the current through the 8.0 Ω resistor.
(4)
(d)
the current through the 10.0 Ω resistor.
(2)
Page 10 of 15
UNIVERSITY OF KWAZULU-NATAL
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
th
12 November 2009
Question 13 (10 marks)
A 6 V battery has an internal resistance of 0.5 Ω and is connected to a 5.5 Ω resistance.
(a) What is the current in the circuit when the circuit is closed?
(3)
(b) What is the potential difference across the battery terminals when the circuit is closed?
(3)
(c) What power is dissipated in the 5.5Ω resistor?
(3)
(d) What is the potential difference across the battery when the circuit is open?
(1)
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UNIVERSITY OF KWAZULU-NATAL
th
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
12 November 2009
Question 14 (11 marks)
R
20 V
Loop 1
5.0 A
4.0 Ω
2.0 Ω
3.0 A
4.0 Ω
ε
Loop 2
(a) For the circuit shown above, calculate the current through the 2Ω resistor.
(2)
(b) Use loop1 to determine the unknown resistance R.
(4)
(c) Use loop 2 to determine the unknown emf ε.
Page 12 of 15
(5)
UNIVERSITY OF KWAZULU-NATAL
th
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
12 November 2009
OPTICS
Question 15 (10 marks)
Refractive index:
nzircon = 1.923
nwater = 1.333
A beam of light is passing through a zircon (artificial diamond) and strikes the
zircon edge at an angle of incidence of 35.0˚, as shown in the diagram. The
zircon is placed in water.
(a) What is the angle of refraction in water?
(5)
35º
zircon
water
(b) What is the maximum angle of incidence in zircon for refraction to take place when the
zircon is in water?
(5)
Page 13 of 15
UNIVERSITY OF KWAZULU-NATAL
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
th
12 November 2009
Question 16 (10 marks)
The diagram below shows the position of an object (O) relative to a convex lens with focal
points marked as f.
(a) Complete the diagram accurately so as to show the position of the image.
Show at least 3 rays.
(6)
f
O
f
(b) Is the image you obtained in the diagram, real or virtual?
Give a reason
(2)
(c) Would this arrangement be suitable to display an image such as from an overhead projector?
Give a reason.
(2)
Page 14 of 15
UNIVERSITY OF KWAZULU-NATAL
FOUNDATION PHYSICS EXAMINATION
Course code: PHYS099 and PHYS199
th
12 November 2009
Question 17 (16 marks)
(a) A pin is placed on the left of a diverging lens of focal length 15 cm. There is an image of
the pin 10 cm from the lens, also on the left of the lens.
(i) Find, by calculation, the position of the pin.
(4)
(ii) Will the image be magnified or diminished?
(1)
(iii) Is the image real or virtual?
(1)
(b) Another pin, which is 5.0 cm high, is now placed 30.0 cm to the left of a converging lens
and it forms a real, inverted image which is 2.5 cm high.
(i)
On which side of the lens will the image be?
(1)
(ii)
Calculate the magnification of the image.
(3)
(iii)
Calculate the distance between the lens and the image.
(3)
(iv)
Calculate the focal length of the lens.
(3)
TOTAL 180 marks
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