SECTION C ( 20 MARKS )

Answers to MYE2013 Sec 4 Paper 2
Note: Answers are brief due to urgency of answers needed!
Section A
Question 1
(a) i. Ratchet knob
ii. To prevent overtightening of the anvil and spindle on the object
(b) 3.76 mm
(c) 3.76/50 = 0.0752 mm
Question 2
(a) i. A physical quantity that cannot be derived from any other quantity
ii. m s-2
(b)
Base Quantity
Derived Quantity
Displacement
Time
Velocity
Acceleration
(any one)
(any one)
Scalar Quantity
Vector Quantity
Time
Displacement
Velocity
Acceleration
(any one)
Question 3
(a) i. Change of velocity over time // Rate of change of displacement
ii. Approximately 5 s
(b) Distance = area under graph = 40 m (show working)
(c) Acceleration = gradient = 10 m s-2 (show working)
(d) Same shape but with higher gradient (on Diagram 3)
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Answers to MYE2013 Sec 4 Paper 2
2. Diagram 4.1 shows a cheetah chasing a deer in a wild world. Given that the mass and
velocity of the cheetah and the deer are 60 kg, 20 m s-1 and 70 kg, 15 m s-1 respectively.
Diagram 4.2 shows the cheetah successfully landed its jaws on the deer and both of them
are moving with a same velocity of v m s-1.
Diagram 4.1
Diagram 4.2
Question 4
(a) Displacement over time // Rate of change of displacement
(b) Kinetic energy
(c) Haven’t learnt yet
(d)
m1u1 + m2u2 = m1v1 + m2v2
60(20) + 70(15) = 60v + 70v
v = 17.308 m s-1
(e) i. Principle of conservation of momentum
ii. The total momemtum before collision is equal to the total momentum after
collision provided no external force acts upon the system
Question 5
Haven’t learnt yet
Diagram 6.1 and Diagram 6.2 show two coconut trees, one by the concrete roadside and the
other by the beach. A coconut from each tree falls from the same height and lands on the
ground.
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Answers to MYE2013 Sec 4 Paper 2
Diagram 6.1
Diagram 6.2
Question 6
(a) Falling with gravitational acceleration
(b) i. Impulsive force
ii. Increasing velocity // Constant acceleration
(c) i. The force acting on the coconut that landed on the road is greater than the coconut
that landed on the beach.
ii. The change in momentum of both coconuts are the same
iii. The time of impact of the coconut on the road is less than on the beach.
(d) The lower the time of impact, the greater the force produced in a collision
(e) Impulsive force
(f) Football
3. Diagram 7 shows an airplane flying horizontally with a constant velocity. P and Q are
two forces which maintain the airplane at constant altitude.
Diagram 7
Question 7
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Answers to MYE2013 Sec 4 Paper 2
(a) i. Lift
ii. Weight
(b) P = Q
(c) Balanced forces // Forces in equilibrium
(d) i. Forward thrust must be greater than air resistance
ii. To produce a net force in the direction of the forward thrust
Question 8
Haven’t learnt yet
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Answers to MYE2013 Sec 4 Paper 2
Section B
4. Diagram 9.1 shows two similar lorries, A which has no load and B which has load in front
of an traffic light. When the green light comes on, both lorry moves simultaneously using
the same force. Diagram 9.2 shows the position of the lorries A and B after 5 s.
Diagram 9.1
Diagram 9.2
Question 9
(a) Amount of matter in an object
(b) Mass of lorry B is more than of lorry A. Distance travelled by lorry A is more than of
lorry B. Velocity of lorry A is higher than of lorry B. The greater the mass, the lower
the distance travelled by the lorry, the lower the acceleration.
(c) To accelerate the car, the driver can press the accelerator pedal more. This creates a
greater forward thrust. When the forward thrust is more than the friction of the road,
the car will be able to accelerate.
(d)
Suggestion
Seat and handle should be lower
Attire should be skintight
Material should be low density
Size of tyre should be smaller
Add gears
Question 10
Haven’t learnt yet
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Reason
Better stability // Lower air resistance
when cyclist cycles forward
To reduce air resistance as the cyclist
moves forward
Lighter, therefore able to move faster
To reduce friction with the road
Able to change gears to move faster
depending on terrain
Answers to MYE2013 Sec 4 Paper 2
Section C
5. Diagram 11.1 shows the speed limit and the load limit of heavy vehicles such as buses
and lorries.
80
LEBUHRAYA
90
BDM 3000 kg
BTM 1700 kg
km/j
Diagram 11.1
Question 11
(a) The tendency of an object to remain at rest or to remain moving at constant velocity
(b) Heavy vehicles have higher momentum and higher inertia. Speed limit must be
imposed to reduce momentum, so that the heavy vehicle can stop more easily in an
emergency. This is also to reduce impulsive force in case of a collision. Load limit
must be imposed to reduce inertia, so that the heavy vehicle can stop more easily in
an emergency.
(c)
Suitable characteristic
ABS
2 tyres
5 small tanks
Large space between trailer and tractor
Reason
Able to prevent tanker from skidding
To reduce pressure // To increase friction
with road
To reduce inertia of the oil
Enough space for the oil to come forward
when the tanker comes to a stop
I would choose C because it has ABS, 2 tyres, 5 small tanks and a large space
between the trailer and the tractor.
(d) Haven’t learnt yet
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Answers to MYE2013 Sec 4 Paper 2
Question 12
Diagram 12.1 shows a helmet, gloves and jacket worn by bikers in a motorcycle racing
tournament. Diagram 12.2 shows the scenery when there is a crash that could happen in a
race.
Diagram 12.1
Diagram 12.2
(a) Rate of change of momentum // Change of momentum over time
(b) The helmet, gloves and jacket is to protect the biker in case of an accident or
collision. The helmet is to protect the biker’s head. The gloves are to protect his
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Answers to MYE2013 Sec 4 Paper 2
hands from injury in an accident, as well as friction with the handles. The jacket is to
protect his body from friction with the ground in case he falls down.
(c)
Suitable characteristic
With ABS
Low mass
Low seat height
Higher width of the tyre
Reason
To prevent motorbike from skidding
Able to move faster // greater
acceleration
Higher stability
Higher stability
I would choose S because it has ABS, low mass, low seat height and high width of
the tyre.
(d) i. a = (v-u)/t = (50-0)/10 = 5 m s-2
ii. F = ma = 220 x 5 = 1100 N
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