JAMES RUSE AGRICULTURAL HIGH SCHOOL
Transcript of JAMES RUSE AGRICULTURAL HIGH SCHOOL
JRAHS Physics Year 11 Half Yearly Assessment Task - Term 2 2012 page: 1
JAMES RUSE AGRICULTURAL HIGH SCHOOL
Student No. ……...........................…..
Half-Yearly Assessment Task
TERM 2, 2012
PHYSICS Theory Paper
General Instructions
Reading time – 5 minutes
Working time – 50 minutes
Write using black or blue pen
Draw diagrams using pencil
Write your Student Number on the Part A Answer Sheet and the Part B Question and Answer book
Total marks for this paper – 570
The Theory paper has two Parts: A and B
Part A Total marks 12
Attempt all questions
Allow about 12 minutes for this part
Part B Total marks 45
Attempt all questions
Allow about 38 minutes for this part
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PART A: Multiple Choice
1. A car travels 40.0 km due south then 40.0 km due west.
What is the magnitude and direction of the car’s displacement?
Magnitude Direction
(A) 80.0 km West
(B) 56.6 km West
(C) 56.6 km South West
(D) 80.0 km South West
2. Which one of the following is a scalar and vector quantity respectively?
(A) Impulse and Power
(B) Energy and Momentum
(C) Force and Acceleration
(D) Mass and Time
3. A swimmer who is able to swim at 1 m s-1
, wishes to arrive at a point directly
opposite her starting point when she crosses a river which is flowing at 0.6 m s-1
East . In which direction must she head and what will be her resultant speed?
(A) and √ m s-1
(B) and √ m s-1
(C) and √ m s-1
(D) and √ m s-1
4. A ball thrown vertically upwards from the ground takes 2 s to reach maximum height.
Assuming there is substantial vertical air drag on the ball, how does the time of flight
for the upward journey compare with that of the downward journey?
(A) It takes 2 s to come down.
(B) It takes less than 2 s to come down.
(C) It takes more than 2 s to come down.
(D) It takes substantially more than 2 s to come down.
5. The kinetic energy of a 4 kg object is . What is the kinetic energy of an 8 kg object
which moves at twice the speed of the 4 kg object?
(A)
(B)
(C)
(D)
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6. Modern automobiles are tested for collision safety using models of human beings
often called crash test dummies. These "dummies" are actually quite "smart." They
are often fitted with sensor devices that can record their motion and force of impact
during an automobile collision.
When the car accelerates from a standing start, the crash test dummy appears to be
pressed backward into the seat cushions. Which of the following best explains why
this happens?
(A) The crash test dummy gets lighter as the car accelerates.
(B) The car is moving forward faster than the crash test dummy.
(C) There is no reaction to the force of the car taking off.
(D) Gravity is pulling the crash test dummy in the direction the car is moving.
7. Two identical spring-balances P and Q are connected by pieces of string to a fixed
wall as shown below.
A horizontal force of 100 N is exerted on spring-balance Q.
What will be the reading on spring-balances P and Q?
(Assume that the weight of the balances and the string is negligible and that the
system is stationary.)
Spring-balance P Spring-balance Q
(A) 0 N 100 N
(B) 200 N 200 N
(C) 50 N 50 N
(D) 100 N 100 N
wall
Q P
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8. A ball is thrown out of the passenger window of a car moving to the right (ignore air
resistance). If the ball is thrown out perpendicular to the velocity of the car, which of
the following best depicts the path the ball takes, as viewed from a stationary observer
above?
(A)
(B)
(C)
(D)
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9. Two blocks of masses 3 kg and 2 kg, connected by a light inextensible string are
resting on a smooth horizontal surface. A horizontal force of 10 N is applied to the
right as shown in the diagram below.
Assuming the system moves to the right, what is the tension, T in the string and the
acceleration, of the system?
Tension, T
(N)
Acceleration, a
(ms-2
)
(A) 4 2
(B) 15 5
(C) 6 2
(D) 10 5
10. Circular waves are created in a sink full of water by repeatedly dipping your finger.
What happens to the wavelength, frequency and speed of the wave as you move your
fingers faster?
Wavelength Frequency Speed
(A) Increases Decreases Stays the same
(B) Stays the same Increases Decreases
(C) Decreases Increases Stays the same
(D) Stays the same Decreases Increases
3 kg 10 N 2 kg
T
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11. The diagram below shows a transverse travelling wave in a string. The wave is
moving from right to left and a particular moment in time ( is shown. At the
moment shown, point has a displacement of zero and point has a maximum
displacement.
Which one of the following gives the ensuing direction of motion of point and ?
(A) moves downwards, moves upwards
(B) moves downwards, moves left
(C) moves upwards, moves upwards
(D) moves left, moves right
12. Compressions and rarefactions are characteristics of sound waves. Which statement is
correct?
(I) A compression is a volume of increased air pressure.
(II) A rarefaction is a volume of reduced air pressure.
(III) Compressions and rarefactions correspond to troughs and crests respectively
of a transverse wave.
(A) (I) only
(B) (II) only
(C) (I) and (II) only
(D) (I) and (III) only
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Student Number : …………………
Part A Answer Sheet Total marks: 12
A B C D
1
2
3
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5
6
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8
9
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11
12
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PART B: Extended Response Marks
13. A car with mass 1500 kg is travelling at 60 km h-1
, east. It collides head on with an
identical car travelling at 80 km h-1
in the opposite direction. Assume the cars lock
together and move off as a combined wreck.
(a) Find the velocity of the wreck immediately after the collision. (3)
( … (law of conservation of linear momentum)
(
(West)
(b) Is kinetic energy conserved in this situation? Justify your reasoning, without the use
of calculations. (2)
No, as the collision is inelastic (since the cars lock together).
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Marks
14. A hot-air balloon is rising vertically at a speed of 10 m s-1
. An object is released
from the balloon. The graph shows how the velocity of the object varies with time
from the time it leaves the balloon to the time it reaches the ground four seconds
later. It is assumed that the air resistance is negligible.
(a) Use the graph to show that the object continues to rise for a further 5 m after it is
released from the balloon. (2)
Time taken to reach maximum height is 1 s, at which time its speed is zero. Hence
from the graph, the displacement in the first second is given by the area under the
curve from
i.e. Displacement =
-40
-30
-20
-10
10
20
Velocity ( m/s)
0 Time (s) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
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Marks
(b) Determine the total distance travelled by the object from the time it is released
until it hits the ground. (2)
Total distance = area under graph =
(
(c) Hence determine the object’s final displacement from its point of release from the
balloon. (2)
Final displacement =
( ( ( )
(d) Use the axes below, sketch a graph showing the object’s acceleration as a function
of time from the time it leaves the balloon to the time it lands on the ground.
Include any critical values on the axes. (2)
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Time (s)
Acceleration ( m/s2)
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Marks
15. Consider a car rounding a flat curve, as shown below.
(a) Indicate on the diagram, all the forces acting on the car at the instant it rounds the
bend. Provide the name and direction of the force/s. (3)
(b) Suppose a car rounds a circular bend and takes 3.5 minutes to go once around.
Determine at what speed the car travels around the bend, if the radius of the bend is
360 m (2)
Hence speed of car is 11 m/s (2 sf) or 39 km/h
(c) Calculate the magnitude and direction of the acceleration of the car as it travels
around this bend. (2)
(directed towards the centre of the road/bend)
Normal/Reaction Force
Centripetal Force
Weight Force Driving Force
Drag/Air resistance
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Marks
16. An elevator rises upwards with an acceleration of 2 m s-2
. A passenger of repute of
mass 60 kg is standing on a bathroom scale inside the elevator, as shown below.
(a) In the space provided draw a simple diagram to show all the forces acting on the
passenger. (2)
(b) What is the reading on the bathroom scale (in N) as the elevator accelerates upwards?
Justify your reasoning with calculations. (2)
But by Newton’s 2nd
law
(
(
Hence reading on bathroom scale is 708 N
(c) Assuming that the cables supporting the elevator were to snap, what will be the
reading on the bathroom scale? (1)
Zero
DIAGRAM
Normal force
Weight
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Marks
17. A black billiard ball which is struck head on by a white cue ball drops into the pocket
of the billiard table. The cue ball remains stationary after striking the black ball.
(a) Explain, using relevant physics principles why the cue ball remains stationary after
striking the black ball. (2)
Since the collision is perfectly elastic, both linear momentum and kinetic energy are
conserved. Hence all the momentum and kinetic energy are transferred to the black
ball, resulting in the cue ball being stationary after the collision.
(b) If the cue ball was in contact with the black ball for 0.03 s, while a constant force of
100 N was exerted on the black ball, determine the speed with which the cue ball
struck the black ball. Assume the mass of each of the balls is 170 g. (2)
(
(
Hence speed of the cue ball just before impact is 17.6 m/s
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Marks
18. A 1200-kg car accelerates uniformly from 5.0 m s-1
east to 12.0 m s-1
east in 2.0 s.
During this time the car travels 17.0 m.
(a) Calculate the average acceleration during this time interval. (2)
(b) Determine the net force acting on the car during this time interval. (1)
(c) If the car experiences a constant retarding force of 200 N, calculate the work done by
the engine during this time. (2)
19. Identify one safety feature in cars and explain using the relevant Physics principles
how its purpose is satisfactorily achieved. (3)
* Airbags/seatbelts/crumple zones/side impact beams/ABS brakes, traction control
* Physics principle
* How achieved
E.g.
Airbags are deployed during a sudden change in motion of a vehicle. The airbags
form a barrier between the passenger and the dashboard/windscreen. The impulse or
change in momentum imparted to the passenger remains the same. However from
, the time the passenger is in contact with the airbag is
substantially increased, thereby reducing the contact force, and eventually reducing
the probability of serious injury.
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Marks
20. State, using a flow diagram, the energy transformations that occur in any one of the
following devices:
(i) mobile phone
(ii) television
(iii) fax/modem (2)
(i) Mobile phone:
(ii) Television:
(iii) Fax/modem:
21. Inertia can be dangerous for a car either at rest or when moving. Describe two ways in
which the danger may arise for each case. (2)
If the car at rest is struck by another vehicle at the rear, then by Newton’s first law
(inertia), the passenger will tend to remain at rest, while the car moves forward due to
the impact. The reaction to this forward motion results in a reverse force on the
passenger, causing whiplash (neck/back injury), hence the danger.
For a car that is moving forward, and struck by another car from the front, the
passengers tend to continue to move forward due to the law of inertia. This causes the
passengers to either crash into the dashboard/windscreen/airbags, resulting in injury.
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22. A student is studying water waves. The variation with time of the displacement of
a particle in the wave is shown below.
The distance of the oscillating particles from the source of the waves is measured. At a
particular time, the variation of the displacement with distance is shown below.
For the water wave, determine the
(a) period of vibration, (1)
(b) wavelength, (1)
(c) speed, (2)
END OF EXAM