Assessment Schedule – 2010
Physics: Demonstrate understanding of mechanics in one dimension (90183)
Note: Minor computational errors will not be penalised. A wrong answer will be accepted as correct provided there is sufficient evidence that the mistake is not due to a lack of understanding. Such evidence includes:
• the last written step before the answer is given has no unexpanded brackets or terms and does not require rearranging.
• the power of any number that is multiplied by a power of 10 is correct.
Correct units and significant figures are required only in the questions that specifically ask for them.
Italics indicate replacement evidence.
Evidence Statement
Question Evidence Achievement Achievement with
Merit Achievement with Excellence ONE
(a) v= !d
!t = 100
11.5=8.69=8.7 m s"1
2 Correct working and
answer.
(b)
Since Terry starts from rest and gains speed OR he is accelerating
1 Correct curve as shown
OR
Acceleration.
1 Achievement plus correct reason.
(c) Distance travelled by Liam
= Area under the graph from 4 to 10 s
= 12 × 6
= 72 m
2 Shows evidence of using the concept of area under the graph.
2 Correct working and answer.
(d) Ek = ½ m × v2 = ½ × 72 × 122 = 5184 J
2 Correct working and answer.
(e) Ek = ½ m × v2 = ½ × 78 × 42 = 624 J
P=W t = 624
0.75 = 832 W
OR
Acceleration = Gradient a= 4
0.75=5.33 m s!2
Force = ma = 78 × 5.33 = 416 N W = F × d = 416 × 1.5 = 624 J
P=W t = 624
0.75=832 W OR if rounded a:
Force = ma = 78 × 5.3 = 413.4
and W will be
W = F × d = 413.4 × 1.5 = 620.1 J
P=W t
=620.1 0.75
=826.8
2 Correct working and answer for Ek.
OR
2 two steps incorrect Note F = mg
Only Achievement.
2 Correct methods and working but wrong answer.
Ie used av v = 2 m s–1 to give P = 208 W OR
2 one step incorrect
Eg a calculated incorrectly from
a= !v t
2 Correct working and answer.
OR
2 Correct working and answer for power.
(f)
SPEED.
Liam ran at a greater speed than Jonathan (by 0.5 m s–1) for the first 4 s.
Both have the same speed at t = 4 s of 12 m s –1.
Between 4 – 10 s Liam ran at a constant speed (of 12 m s–1), while Jonathan had a greater speed between 4 – 8.25 s with maximum of 13.2 m s–1
Both of them finished off with the same speed of 12 m s–1 from 8 s.
ACCELERATION
Both of them have similar acceleration between 0 – 4 s as both gradients approx. the same.
Liam accelerated at 4.5 m s–2 and Jonathan accelerated at a higher rate at 5.33 m s–2 (for the first second) Jonathan accelerated for a longer period of time until 5.75 s. but Liam accelerated for 4 s.
Liam had average acceleration of 3m s–2 and Jonathan had average acceleration of 2.3 m s–2
Accelerate at constant speed WRONG.
1 Both
ACCELERATION SPEED
Statement with no values.
1 Both
ACCELERATION SPEED
With partial reasons /
justifications from graph
Ie times with no values, or values with no times OR acceleration
the same with no reference to gradient.
IF just described each path with no comparison then M.
1 Both
ACCELERATION SPEED
Compared with
values and times for velocity AND
times and / or comment for acceleration.
TWO
(a) Air resistance / air friction / drag.
Gravity or weight
1 Either answer is correct.
1 Both answers are correct.
(b) Fg = mg = 65 × 10 = 650 N Funbalanced = 65 × 7.2= 468 N Upward force = weight – Funbalanced = 650 – 465
= 182 N
2 Correct working and answer for weight.
OR
ONE correct calculation.
2 Correct working and answer for both weight and unbalanced force.
OR correct process with a single error.
2 Correct working and answer for upward force.
(c) Ep = mgh = 65 × 10 × 50 = 32500 J 2 Correct working and answer.
2 Correct working and answer.
(d) 37 700
4712.5 4712 N 8
F W
= d = = =
Direction: upwards
ONE direction.
(e)
The padding does not affect the force, but increases the area of skin that the force acts on. Because P= F
A, increasing the area reduces the pressure on her skin.
Without the padding, same force acts on a smaller area, so the pressure on her skin increases.
1 PRESSURE is greater without padding.
OR
PRESSURE less with padding.
1 Pressure decreased AND ONE of
F same A increased
1 Complete answer COMPARING both situations.
F same A increased P decreased
Must mention both with and without padding
THREE
(a) F = mg = 420 × 10 = 4200 N 4200 13
323 A F
= P = = m2
2 Correct working and answer for weight.
OR
Uses m for F.
2 Correct working and answer.
(b) Velocity of the boat / 6 m s–1
Velocity of current / 2 m s–1
Velocity of the runner / 1 m s–1
1 Any two vectors are drawn and labelled correctly.
OR
Drawn and labelled but sizes incorrect.
1 All vectors are drawn and labelled correctly.
Relative sizes correct.
(c) 6.0 + 2.0 + 1.0 = 9.0 m s–1
2 Correct answer
(d) W = F × d = 1 800 × 6.0 = 10 800 J Ep gained = work done
m × g × h = 10 800 m × 10 × 3.2 = 10 800
10 800 337.5 m= 32 = kg OR find v from mgh = ½ mv2 Then put into F × d = ½ mv2
2 Correct working and answer for W.
OR
ONE correct calculation.
2 Correct working and answer for W.
AND uses the idea of energy conservation only.
2 Correct working and answer for m.
(e) (i) 1. The advantage of using a ramp is that FORCE is lessened over a longer DISTANCE. (W = F × d) for the same WORK.
(e) (i) The wheels minimise FRICTION, so less ENERGY lost / less energy used so less FORCE needed /
1 states
less force OR same work
AND
states less force OR
less work used / lost.
1 links any TWO of the given points
from either (i) or (ii).
1 links ALL the points clearly
from either (i) or (ii).
Judgement statement
Achievement Achievement with Merit Achievement with Excellence
Criterion 1 4 A1 4 M1 2 M1 + 2 E1
Criterion 2 6 A2 3 A2 + 3 M2 3 A2 + 1 M2 + 2 E2
