exta class ppt
TRANSCRIPT
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1 D
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2 C
Distance moved parallel to the direction of force
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3 A
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4 C
At 2.6s, h = 0.6m
Displacement = 1.30.6
=0.70m
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5 D
In x-t graph, gradient = velocity
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6 A
Graph starting from zero
Straight lines, parallel to each other
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7 C
Up thrust > Weight
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8 B
300 N
10,200-9800
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9 C
E = F l / A x
x 1 /E
xs / xb =Eb/ Es= Eb/ 2 Eb= 0.50
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10 C
F = k x
x = 0.13 0.040
k = F / x
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11
(a) Weight of the water = m g
= v d g
= 5 x 10-3
x 0.010 x 1000 x 9.81
= Weight = 0.49 (N)
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(b) weight (of cork) = weight of displaced water
= 0.49 or 0.5 N
weight (of cork) = upthrust
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12
(a)(i)Hard
resistant to indentation/scratching Or
surface is resistant to plastic deformation
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(ii)Stiff
high Youngs ModulusOr
large force / load / stress for (small) extension /
strain / deformationOr
(large) force / load / stress for small extension /
strain / deformation
(not resistant to, hard to bend)
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(iii)High tensile strength
withstand/bear/undergo a large stress/force
(under tension) before breaking/fracture
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(b) (Large stretching) force/stress/tension
appliedOr wire is being stretched/taut
Will not plastically /permanently deform Or will
return to original length(when forceremoved)
Idea that thepitch/frequency/tone/tune/sound/note willalter.
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14
a(i)
Energy = power time
Energy = 4.2 W 0.4 s
Energy = 1.68 (J)
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(ii)
Ek= mv2
V = 6.5 ms-1/ 5.9 ms-1
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(iii)
Energy is dissipated to heat
Or work is done against friction
Or not all the energy becomes kinetic energy
Or air resistance on car
Or friction between car/wheels/pin and track
Or resistance in motor
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(b)
No resultant force is acting on the car
(Car) continues moving: in a straight line
Or in same direction Or with same velocity.
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15
(a)As the temperature increases, the viscosity
decreases
at a decreasing rateOr
the rate of decrease is greater at lower
temperatures Or exponentially
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(b)(i)
F = 6 r v
= F /6 r v
= N / m m s-1
= N m-2s = Pa s
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(ii) 6 r v = weight of the sphere = m g
= 1.12 x 10-3 Pa s ( from the graph)
V = m g / 6 r
= 3.7 ms-1
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16
(a)Consider the half motion
v = u + at
0 = 2.8 + (-9.81) tt = 0. 285 s
Total time = 0.285 x 2
= 0.57 s
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(b) Horizontal = Horizontal velocity x time
distance
= 8 x 0.6
= 4.8 m
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(c)At the time of landing,
u = 2.8 ms-1, a = 9.81 ms-2, s = 0.50 m
v 2= u2+ 2 a s
v = 4.2 ms-1
v = u + att = 4.22.8 / 9.81 = 0.14 s
Distance = v x t = 8 x 0.14
=1.1m
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17
(a)(i)Use of E= m g h
= 810 9.81 6.0
= 47, 700 (J)
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(ii) (useful) energy = 40total energy
transferred transferred
= 40 / 100 x 47,000
= 19 100 J
Resistive force , F = E /d = 19,100/0.20
= 9.6 x 104N
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(b)(i) Stress = Force / Area
Strain = Extension / Original lengthYoung modulus,E = F l /A x
= 2
x (compression) = F l / A E= 0.0083 (m)
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(ii)
Energy stored, E = F x
= x7 x 10 5 x .01
= 3.5 x 10 3 J
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(iii) 1.
Graph:
Permanent/plastic compression/deformation
Or does not return to its original length/shape
Effect:
Becomes too thin
Or will not compress
Or no longer elastic
Or becomes brittle
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2.
More work done in loading than unloading the
wood
Or more energy is absorbed/stored than released
Or the area between the lines shows energy is
dissipatedOr the area while applying the force > the areawhile releasing
Or (the area in) the hysteresis loop shows energyis dissipated
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18
9(a)
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(b)(i)
L cos 20 = mg
L = 0.66N
L sin20
L
cos
20
mg
20
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(ii)
L sin 20 = ma
a = 0.66 x sin 20 / 0.063
a = 3.58 m s-2