2013 Technological Studies. Advanced Higher. Finalised Marking Instructions

Transcription

1 03 Technological Studies Advanced Higher Finalised Marking Instructions Scottish Qualifications Authority 03 The information in this publication may be reproduced to support SQA qualifications only on a noncommercial basis. If it is to be used for any other purposes written permission must be obtained from SQA s NQ Assessment team. Where the publication includes materials from sources other than SQA (secondary copyright), this material should only be reproduced for the purposes of examination or assessment. If it needs to be reproduced for any other purpose it is the centre s responsibility to obtain the necessary copyright clearance. SQA s NQ Assessment team may be able to direct you to the secondary sources. These Marking Instructions have been prepared by Examination Teams for use by SQA Appointed Markers when marking External Course Assessments. This publication must not be reproduced for commercial or trade purposes.

2 Part One: General Marking Principles for Technological Studies Advanced Higher This information is provided to help you understand the general principles you must apply when marking candidate responses to questions in this Paper. These principles must be read in conjunction with the specific Marking Instructions for each question. (a) (b) Marks for each candidate response must always be assigned in line with these general marking principles and the specific Marking Instructions for the relevant question. If a specific candidate response does not seem to be covered by either the principles or detailed Marking Instructions, and you are uncertain how to assess it, you must seek guidance from your Team Leader/Principal Assessor. Marking should always be positive ie, marks should be awarded for what is correct and not deducted for errors or omissions. GENERAL MARKING ADVICE: Technological Studies Advanced Higher The marking schemes are written to assist in determining the minimal acceptable answer rather than listing every possible correct and incorrect answer. The following notes are offered to support Markers in making judgements on candidates evidence, and apply to marking both end of unit assessments and course assessments. Page

3 Temperature ( C) Temperature ( C) Temperature ( C) Section A Marks Q (a) (i) Time (ii) Time (iii) Time (b) Integral removes the offset. (c) Derivative reduces hunting. (0) Page 3

4 Q (a) Rail is not symmetrical on each side of neutral axis (b) 80 kn L FL M 8 I = mm 4 σ max = 50N/mm (tensile) y = 79 3mm compression y = 74 7m tension M I y M I y For tension: 5000 M T = 747 8M L = F Nmm L T = L T = 794mm Max. Allowable span =.79m 7 Page 4

5 Q (c) M I σ y E R R = M EI R c = = mm = 05m OR (alternative answer for full marks) R T = = mm = 99 6m 6 () Page 5

6 Q3 (a) main: call adcread movlw d 8 subwf DATA btfsc STATUS, Z goto main btfss STATUS, C goto low call RAISE goto main for both low: call LOWER goto main given above 0 (b) RAISE: movlw d 4 movwf COUNTER loop: movlw b mark for label movwf PORTB movlw d call wait movlw b movwf PORTB movlw d 99 call wait decfsz COUNTER, F goto loop return () Page 6

7 Q4 Marks Page 7 5V JK (Units) 5V JK (Tens) Q CLK (Units) Q CLK (Tens) Q AND (Units) AND CLK (Tens) AND OR Units SET Set to 9 Units RESET Tens SET Set to 5 Tens RESET Inverter to CLK (Tens) (3)

8 Q5 read: bcf STATUS, C movlw d 8 movwf COUNTER loop: bcf STATUS, C btfss PORTB, 3 bsf STATUS, C rlf BUFFER, F movlw d 3 call pause decfsz COUNTER, F goto loop movlw d 4 movwf COUNTER loop : bsf PORTB, 7 movlw d 50 call pause bcf PORTB, 7 movlw d 50 call pause decfsz COUNTER, F goto loop return (8) Page 8

9 Q6 (a) A Push switch sets SR, enabling counter; disables reset of counter. B Counts clock pulses. C Decodes binary number into decimal. D AND gates cause reset of SR on count 7; disables and clears counter 3 E Logic Array decodes decimal into sequence of machine. 8 (b) Counter Count Tail Wag Walk Left Eye Right Eye Bark Flip RESET each correct column for reset on (5) Page 9

10 Q7 (a) (i) Distance (m) Distance (m) (ii) 475 9mFrom LHE 50 (b) From LHE 0 5m : ( ) ( ) = 0 65 knm m : (47 5 ) ( 5 0 5) = 35 knm 5m : (47 5 5) ( ) = 43 5 knm m : (47 5 ) ( 5 ) = 45 knm 5m : (47 5 5) ( 5 5 5) (0 5 30) = 5 6 knm Distance from left hand 0m 0 5 m 5m m 5m 3m end (m) Bending moment (knm) (8) Page 0

11 Q8 (a) (i) Three (push to make) switches each send a signal to ss(ii) (ii) (iii) (iv) (v) Three SR bistables each set by a contestant, lights their lamp. All reset by quizmaster AND gate triggers monostable; disables contestant switches. One contestant disables other two Monostable provides a signal to astable, when triggered low. When output from (iv) goes high, astable is enabled; buzzer sounds, at set frequency for a fixed time. (b) Frequency: f 44 R R C f = f = 480 Hz (4) Page

12 Q9 (a) main: btfss PORTB, goto main loop: bsf PORTB, 7 movfw MARK call pause bcf PORTB, 7 movfw SPACE call pause btfss PORTB, 4 goto decrease movlw d addwf MARK, F decrease: btfss PORTB, 3 goto opto movlw d subwf MARK, F opto: btfss PORTB, O goto opto incf COUNT rlf COUNT, F rlf COUNT, F bsf PORTB, 6 movfw COUNT call pause bcf PORTB, 6 btfsc PORTB, 5 end goto main 4 Page

13 Q9 (b) (i) (ii) V V out out RC V in dt Vin t RC R R R 39 39k 6 47 µf V cc 0 k - 0 k OV + -Vcc + Page 3

14 Q9 (c) Vout 9V 00359Vincrements = 6 Ro Ro R o = 550 kω Resistor ladder is: R o = 550 kω R = 75 kω R = 638 kω R 3 = 39 kω R 4 = 59 kω R 5 = 79 7 kω R 6 = 39 8 kω R 7 = 9 9 kω lsb R0 5k 0 k 0 k etc 0V 0V Vout msb R7 3 8 (40) Page 4

15 Q0 (a) Sub-system A: The voltage divider (R, R and R f ) provide a reference into the non-inverting input. When non-inverting > inverting input, output is 5V. Rate of charge of capacitor determined by resistance of proximity sensor (frequency). When inverting input > non-inverting, output goes low, capacitor discharges and device oscillates. Soft Stop is caused by proximity sensor resistance increasing causing frequency to decrease. Sub-system B: Sub-system A clocks the 4 D-types. Q from B causes a zero on D for two pulses, then two s repeating. Coils are energised by Q going high. Any 8 points at mark each 8 (b) Switch-off threshold = 3 5V V out is presently high: V out = 5V 5 v 9 k Rf 5 v 9k and R f in parallel V lower = 3 5V V upper = 5V 0 k 3 5 v Rp Rp kω Rf Rf (9 + R f ) 4 9 = 9 R f R f = 9 R f 4 7 R f = 38 6 R f = 8 0 kω 8 Page 5

16 Q0 (c) 5V clock 0V 5V Coil A 0V 5V Coil B 0V 5V Coil C 0V 5V Coil D 0V 8 (d) (i) A F B FL at A FL 3 3EI at B M = FL = = 0 6 Nmm I = My/σ = ( )/00 = mm = (BD 3 /) (bd 3 /) = (80 4 /) (bd 3 /) = ( (bd 3 /) = d 4 / (b = d) d 4 / = d 4 = d = mm t t = 58 mm (d) (ii) 3 FL δ 3EI δ = ( )/( ) δ = ( 0 )/( ) δ = 4 5 mm 4 (40) Page 6

17 Q (a) alert: clrf DISTRESS call S_TEST call O_TEST (for both S ) call S_TEST movlw d 3 subwf DISTRESS btfsc STATUS, Z bsf PORTB, 5 end 8 (b) S_TEST: clrf DOTCOUNT movlw d 3 movwf COUNTER loop: btfss PORTB, O goto loop movlw d call wait btfss PORTB, O incf DOTCOUNT, F decfsz COUNTER, F goto loop movfw DOTCOUNT xorlw d 3 btfsc STATUS, Z incf DISTRESS return 4 Page 7

18 Q Structural Tower (c) 3KN 0KN NA M M M 3 ΣMNA 0 (0 4) (M ) 0 M 40 0kN(STRUT) 4 NB ΣMNB 0 (0 ) (3 ) (M perp ) M3 0 M M 3 5 7kN (TIE) 6 m 45 5 sin 60 perp 88 m 45 perp perp 88sin 60 perp 45m 60 adj opp hyp = 8 = 88m 3KN 0KN 0KN NA M 5.6KN ΣV cos 5 M cos M M M 6 35 kn (TIE) 6 8 (40) [END OF MARKING INSTRUCTIONS] Page 8