Physical Science Paper 1 Physics - May 2014

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Physical Science Paper 1 Physics - May 2014

BISHOPS May 2014Physical Sciences/P1

BISHOPS

GRADE 12

PHYSICAL SCIENCE PAPER 1 – PHYSICS - MAY 2014

Examiner: KW Time: 3 hr

Moderator: PWMarks: 150

This paper consists of 10 pages (including this cover sheet) and a data sheet.

General Instructions:

  1. Write YOUR NAMEand YOUR TEACHER’S NAME clearly on your answer sheets.
  2. Answer ALL the questions.
  3. Start EACH question on a NEW page.
  4. Number the answers correctly according to the numbering system used in this question paper.
  5. Leave ONE LINE between two sub-questions, for example between QUESTION 2.1 AND 2.2.
  6. You may use a non-programmable calculator and appropriate mathematical instruments.
  7. You are advised to use the attached DATA SHEETS.
  8. Show ALL formulae and substitutions in ALL calculations.
  9. Round off your final numerical answers to a minimum of TWO decimal places.
  10. Give brief motivations, discussions, et cetera where required.
  11. Write NEATLY and LEGIBLY.

QUESTION 1: MULTIPLE-CHOICE QUESTIONS

Four options are provided as possible answers to the following questions. Each question has only ONE correct answer. Write only the letter (A – D) next to the question number (1.1 – 1.10) on your answer paper, for example 1.11D.

1.1In the absence of friction, the acceleration of an object close to the surface of the earth in free fall is…

Aconstant

Bdecreasing constantly

Cdirectly proportional to the mass of the object

Dequal to the change velocity of the object

1.2A non-zero net force acting on an object always results in …

Achanging the potential energy of the object

Bchanging the weight of the object

Cchanging the momentum of the object

Dchanging the mass of the object

1.3If an observer hears a siren from an ambulance that is moving towards him, which of the following statements will NOT apply?

Athe wavelength of the waves will have shortened

Bthe frequency of the waves will have increased

Cthe speed of the waves will have increased

Dthe pitch of the waves will have increased

1.4A ball falls from rest to the floor and bounces once almost reaching the height from which it fell. If down is taken as the positive direction, which one of the following quantities changes from positive to negative during this motion?

Aacceleration

Bvelocity

Cdisplacement

Dpotential energy

1.5Two vehicles X and Y move towards each other and collide head on. The mass of X is double the mass of Y. The collision stops both vehicles completely and after the collision both vehicles remain stationary. Which of the following statements is NOT TRUE.

AX and Y had equal kinetic energies before the collision.

BThe momentum of X and Y were equal in magnitude before the collision.

CThe magnitude of X’svelocity was half the magnitude ofY’s velocity before the collision.

DThe impulse experienced by X is equal and opposite to the impulse experienced by Y.

1.6P and Q are two point charges. A negatively charged particle “x” is placed between P and Q as shown in the diagram. The net force on “x” as a result of the charges on P and Q is represented by the arrow (F). Which of the combinations below shows possible charge combinations on P and Q?

P / Q / Charge magnitude
A / Positive / positive / P > Q
B / Positive / negative / P < Q
C / Negative / positive / P > Q
D / Negative / negative / P < Q

1.7Two metal spheres exert a gravitational force of F on each other when on the surface of the earth. If the spheres are taken to a planet which has double the mass of earth and double the radius of the earth, which of the following gives the correct force of gravitational attraction between the two metal spheres?

A2 F

BF

C½ F

D4F

1.8A box is dragged to the top of an inclined slope by a force F as shown in the diagram below. If the net work done during this process is ZERO then…

AThere is no work done against friction.

BThe work done against friction is equal to the work done against gravity.

CF is greater than the force of friction.

DThe work done by F is equal to the work done against friction.

1.9The circuit below has two identical bulbs connected in parallel to a battery comprised of 3 cells each having internal resistance.

If one of the bulbs is removed from the circuit the reading on the voltmeter would…

AINCREASE

BDECREASE

CREMAIN UNCHANGED

DBECOME ZERO

1.10A model rocket is launched from a launch pad and it accelerates with a constant force for a minute before the engine stops firing when it runs out of fuel. Which of the statements is true for the object as it accelerates?

AThe potential energy gain is equal to the gain in kinetic energy.

BThe work done against friction is greater than the work done by the motor.

CThe acceleration of the rocket is always less than 9.8 m.s-2.

DThe acceleration of the rocket is greatest just before the engine stops firing.

10 x (2) = [20]

QUESTION 2 (Start on a new page)

On the Orange River rafting trip, rafts are lowered down a cliff at a constant speed by means of a makeshift pulley system as shown in the sketch. The packed raft has a mass of 500 kg and the slope is at an angle of 20o to the vertical.

2.1State Newton’s First Law of Motion in words.(2)

2.2Draw a labelled free-body diagram indicating all the forces on the raft as it moves down the inclined plane. The length of the arrows must represent the relative sizes of the forces. (4)

2.3Calculate the magnitude of the force offriction between the raft and the cliff if the coefficient of friction between the two surfaces is 0,65. (5)

2.4How would the force of friction be affected if the angle of the slope to the vertical increased from 200 to 300? State only INCREASE, DECREASE or NO CHANGE. (1)

2.5If the raft needs to decelerate at a rate of 0.5 m.s-2 in order to be brought to a halt at the bottom of the slope, calculate the magnitude of the tension in the cable in order to achieve this. (6)

[18]

QUESTION 3 (Start on a new page)

In the movie Gravity an astronaut becomes separated from the space station in which they were working. Assume this happened in reality and the space station had a mass of 1000000 kg while the astronaut’s mass was 85 kg.

3.1Calculate the force of gravitational attraction between the astronaut and the space station if the distance between the centre of the space station and the astronaut was 13 m. (4)

3.2Calculate the initial acceleration of the astronaut due to the attraction of the space station if the astronaut is 13m from the centre of the space station. (Assume the space station remains stationary.) (3)

3.3State whether you would expect the acceleration that you have calculated in 3.2 to INCREASE, DECREASE or REMAIN THE SAME as the astronaut approaches the space station. (1)

3.4The astronaut reaches a maximum velocity of 0.03 m.s-1 just before colliding with the space station. Calculate the impulse that would be experiencedby the astronaut if he was brought to a halt by a collision with the space station. (4)

3.5Calculate the magnitude of the force that would be experienced by the astronautif the duration of the collision is 0.1s. (3)

[15]

QUESTION 4 (Start on a new page)

A ball of mass 0.75 kg is thrown vertically up and allowed to move under the influence of gravity until it falls to the floor and bounces a number of times before finally coming to rest. The velocity time graph for the motion of the ball is given below.

4.1What feature of the ball’s motion is represented by the gradient of the graph?(1)

4.2State the initial velocity of the ball.(2)

4.3What is represented by the area under a velocity – time graph?(1)

4.4State what each of the areas indicated A andB on the graph represent in terms of the balls displacement. (2)

4.5Show how you would use these areas to calculate the height from the ground at which the ball was released. (1)

4.6Use relevant equations of motion to calculate;

4.6.1the time taken until the ball began falling back towards earth for the first time.(3)

4.6.2the height above the ground from which the ball was thrown if the first bounce occurred 0.67s after the ball was released. (4)

4.7Using graphical methods (not equations of motion) calculate the height of the first bounce represented by area C in the graph. (3)

4.8Draw the position time graph for the motion of the ball from the time it is released until it reaches the ground for the second time. You do not need to indicate values on the graph. (3)

[20]

QUESTION 5 (Start on a new page)

5.1A cart on a rollercoaster with a mass of 200 kg is pulled up a slope by a conveyer belt at a constant speed of 0.30 m.s-1. With this initial speed the cart then drops down a slope to point Q under the influence of gravity and friction only as shown in the diagram below. At point Qthere is a braking mechanism which brings the cart to a stop at point Rover a distance of 4 m. The cart experiences a constant frictional force of 75.4 N between P and Q.

5.1.1Define a conservative force and identify a conservative force which is in operation in this scenario. (3)

5.1.2Determine the net work done in raising the cart up the slope to point P. Show your working or give an explanation for your answer. (3)

5.1.3Calculate the magnitude of the velocity of the cart on reaching point Q if the distance covered between P and Q is 20.0 m. (6)

5.1.4Use the work-energy theorem to calculate the magnitude of the force that is exerted by the braking mechanism to bring the cart to a halt at R. (5)

5.2A person standing on a floating platform in the sea jumps vertically upward as shown in the picture below.

5.2.1State the principle of conservation of momentum.(2)

5.2.2The person and platform were at rest before the jump and havemasses of65.4 kg and 500.0 kg respectively. The platform is pushed down with a velocity of 0.60m.s-1. (Ignore the any effect or mass of the water and use only energy and momentum principles NOT equations of motion.)

Calculate;

5.2.2.1the velocity of the person as he leaves the platform.(4)

5.2.2.2the height reached by theperson(5)

[28]

QUESTION 6 (Please turn over)

When air is passed across the end of a hollow tube a whistling sound can be produced from the tip of the tube.

In an experiment to measure the speed of sound a researcher sets up a tube which spins anticlockwise in a circle so that the tip of the tube moves at a constant speed of 2 m.s-1. As shown below:

The tip of the tube produces a whistling sound which changes in pitch as it moves relative to the researcher. The researcher records and measures the frequency of this sound. A recorded frequency varies between a maximum of 263.19 Hz and a minimum of 260.0 Hz.

6.1Name the effect which causes the change in pitch.(1)

6.2Which point A, B or C would correspond to the maximum frequency that the researcher measures?

(1)

6.3Explain your answer to 6.2.(3)

6.4How would the frequency of the sound produced when the tube is a point B compare to the actual frequency of the sound produced by passing wind over the tip of a stationary tube at 2 m.s-1? State only HIGHER, LOWER or THE SAME. (1)

fo / = / (v /  / vo) / fs
(v / ± / vs)

6.5In order to use the readings taken to calculate the speed of sound the researcher would write two expressions using the equation:

One of these expressions would be for the maximum observed frequency and one would be for the minimum frequency.

By then combining these two equations using the fact that the frequency of the source remains the same for both situations, the speed of sound can be calculated. Perform this calculation to find the speed of sound. (7)

6.6Explain what is meant by the term ‘Red shift’ and its significance in the study of the universe.(3)

[16]

QUESTION 7

Two small identical metal spheres Q1 andQ2 are fixed in place 4 cm apart in a vacuum. A thirdidentical metal sphereQ3is suspended by a small thread between Q1 and Q2. All three spheres carry electrostatic charges. Q3hangs vertically down as shown as a result of the electrostatic forces due to the interaction of the three charges.

Q1 and Q3 each carry a charge with a magnitude of 4.25 C.

7.1State Coulombs law in words.(2)

7.2If the charge on Q1 is POSITIVE, state the nature of the charges on Q2 and Q3.(2)

7.3Calculate the magnitude of the charge on Q2 so that Q3 hangs vertically as shown.(6)

7.4Calculate the strength of the electric field at Q3 due to the presence ofQ1.(4)

7.5How many electrons have been lost by Q1 to create the+4.25 C charge?(3)

[17]

QUESTION 8

In the electrical circuit shown below the battery has an EMF of 6 V and a total internal resistance of 1 . The total external resistance of the circuit is 9 .

8.1State Ohm’s Law.(2)

8.2Calculate the reading on the ammeter when the switch is closed.(3)

8.3Explain what happens to the reading on the voltmeter when the switch is closed?(2)

8.4Calculate the lost volts in the battery.(3)

The power dissipated in resistor R3 is 5.04 W.

8.5Calculate the resistance of resistor R3.(3)

8.6If R2 is short circuited by connecting a piece of conducting wire between points X and Y, what effect would this have on the lost volts? (1)

8.7Explain your answer to 8.6.(2)

END OF QUESTIONS[16]

G12 Physical ScienceData SheetPAPER 1 PHYSICS

TABLE 1: PHYSICAL CONSTANTS

NAME / SYMBOL / VALUE
Acceleration due to gravity / g / 9,8 m∙s-2
Gravitational constant / G / 6,67 x 10-11 N∙m2·kg-2
Speed of light in a vacuum / c / 3,0 x 108 m∙s-1
Planck’s constant / h / 6,63 x 10-34 J∙s
Coulomb’s constant / k / 9,0 x 109 N∙m2·C-2
Charge on electron / e- / -1,6 x 10-19 C
Electron mass / me / 9,11 x 10-31 kg

TABLE 2: FORMULAE

MOTION

/ OR
OR / OR

FORCE


/ w = mg

WORK, ENERGY AND POWER

W = FΔx cosϴ / OR
OR / Wnet = ΔK OR Wnet = ΔEk
ΔK = Kf – Ki OR ΔEk = Ekf – Eki
Wnc = ΔK + ΔU OR Wnc = ΔEk + ΔEp /
Pave = Fvave

WAVES, SOUND AND LIGHT

/ E = hf OR
E = W0 + K OR E = W0 + Ek where
E = hf and W0 = hf0 and K = ½ mv2max OR Ek = ½ mv2

ELECTROSTATICS

OR

ELECTRIC CIRCUITS


/ q = IΔt
W = Vq
W = VIΔt
W = I2RΔt
/
P = VI
P = I2R

ALTERNATING CURRENT


/ Paverage = VrmsIrms
Paverage = Irms2R

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