Answers to end-of-chapter questions Cambridge International AS Level Physics Cambridge International AS and A Level Physics Chapter P1 PDF

Preview

Summary

Cambridge International AS Level Physics Answers to end-of-chapter questions Answers to EOC questions Chapter P1 ■■ always view from directly above the mark on the track when using a rule [1] 1 a 25.8 ± 3.3 cm or better 26 ± 3 cm [1] (Maximum [8] marks: [4] for the problems, and b 2.80 ± 0.18 cm o...

Description

Accelerat ing t he world's research.

Answers to end-of-chapter questions Cambridge International AS Level Physics Cambridge International AS and A Le... Miss Jennie

Related papers

Download a PDF Pack of t he best relat ed papers 

Turn over basit jawwad

CIE+A-LEVEL

AS&ALevel+Physics+Revision+Guide

Rio Lee Physics IGCSE Duncan20190523 74108 1xlj7ih sudhir chopra

Cambridge International AS Level Physics

Answers to end-of-chapter questions

Answers to EOC questions ■■

Chapter P1 1

2

3

a 25.8 ± 3.3 cm or better 26 ± 3 cm b 2.80 ± 0.18 cm or better 2.8 ± 0.2 cm c 24.0 ± 0.1 g

[1] [1] [1]

a 1.1 ± 0.1 V; 0.7 ± 0.1 V [1] b If R = kl then the two values of k are 0.0440 Ω cm–1 and 0.0467 Ω cm–1. [1] The criterion is that, if the resistance is proportional to length, then the percentage diference in the values of k is less than the percentage uncertainty in the value of V. [1] Percentage diference in k values 0.27 = 0.6% = 0.044 [1] Percentage uncertainty in lowest value of V is 14%, so the data is consistent with R proportional to l. [1] Apart from taking only two readings, which is not enough, it is dificult to: ■■ release the ball without giving it an initial velocity [1] ■■ start the stopwatch as the ball is released [1] ■■ stop the stopwatch exactly as the ball crosses the line [1] ■■ release the ball exactly on the line [1] ■■ measure small times that are not much larger than reaction times [1] ■■ avoid the balling rolling to the side of the track [1] ■■ measure the distance without introducing parallax error [1] Suggested improvements ■■ take readings at about five values of s and 2 ■■ plot a graph of T against s [1] ■■ take a video of the ball rolling down the ramp with a timer in the background and play it back frame by frame [1] ■■ use a metal ball, held to an electromagnet at the same start position each time, turning of the magnet to start the ball [1] ■■ use longer distances [1] ■■ have a groove down the middle of the track [1]

always view from directly above the mark on the track when using a rule [1]

(Maximum [8] marks: [4] for the problems, and the other [4] for solutions / improvements.) 4

a Values for m correct and to the same number of significant figures, or one more than data [1] Values for T correct and to the same number of significant figures, or one more than data [1] Mass / g

0.5

T20 / s

m/g

T/s

20

12.2

4.5

0.610

50

15.0

7.1

0.750

100

18.7

10.0

0.935

150

21.8

12.2

1.090

200

24.5

14.1

1.225

190

24.0

13.8

1.200

1.4 1.2 1.0 0.8 T/s 0.6 0.4 0.2 0.0 0

5

10

15

m / g 0.5

b Sensible axes used and labelled with quantity and unit [1] All points plotted to within half a small square [1] All points close to line [1] Line of best fit correct [1] c Gradient drawn with more than half length of drawn line; value between 0.062 and 0.064 [1] y-intercept between 0.30 and 0.32 [1] d C = value given for y-intercept with unit s, e.g. 0.31 s [1] k = value given for gradient with unit, e.g. 0.063 s g–0.5 [1]

Cambridge International AS and A Level Physics © Cambridge University Press 2014

Cambridge International AS Level Physics

5

a i 127 cm [1] ii 3 cm [1] 2% [1] iii 4.7 s [1] iv 0.1 s [1] 2% [1] b i When l = 40 cm, v = 27 cm s–1; when l = 60 cm, v = 38 cm s–1 [1] ii Two significant figures, as this was the lower of the number of significant figures for s (3 sig. figs) and t (2 sig. figs) [1] s c i, ii k = l = 3.175 and 3.167. The percentage diference in k values is 0.26%. [1] This is less than the percentage uncertainty in s = 2%, so the data is consistent with s proportional to l. [1] d, e See comments for experiment 2, plus the dificulty of measuring to the middle of the trolley for l and s (measure from end of trolley and add on half the length of a trolley found separately), dificulties that may occur as the toy car hits the straight section (have a slightly curved join), and dificulties with the car not running straight (have wheels in grooves) [8] (Marks: [1] for each sensible source of uncertainty, to a maximum of [4]; and [1] for each sensible improvement, to a maximum of [4])

6

a Average value of voltage was 5.9 and uncertainty is ±0.2 or possibly 0.3 V. Percentage uncertainty is between 3% and 5%. [1] –2 b i 0.42 °C V [1] –2 and 0.35 °C V [1] ii Two significant figures, as V was measured to 2 sig. figs and q was measured to 3 sig. figs. Choose the lower number. [1] iii Percentage diference in values of k is 18%. This is larger than the 5% uncertainty in V (which is larger than the percentage uncertainty in the value of θ). Thus the data is not consistent with the suggested relationship. [1]

Answers to end-of-chapter questions

c Only two voltage readings is not enough. [1] The voltmeter reading fluctuates because of contact resistance. [1] The voltmeter reading fluctuates because of a change in mains voltage. [1] The voltmeter reading falls because the resistance of the wire changes as it heats up. [1] The temperature increases ater the switch is turned of (while heat passes from the resistor to the water). [1] (Maximum of [4] marks) d Clean the wires first. [1] Use a car battery. [1] Use a metal whose resistance changes little with temperature. [1] Use more than two voltages and plot a graph of θ against V 2 or calculate more than two values of k. [1] Stir well and take the highest reading on the thermometer ater switching of. [1] (Maximum of [4] marks)

Cambridge International AS and A Level Physics © Cambridge University Press 2014...