Integrated Concepts A 160 − μ F capacitor charged to 450 V is discharged through a 31.2-k Ω resistor. (a) Find the time constant. (b) Calculate the temperature increase of the resistor, given that its mass is 2.50 g and its specific heat is 1 .67 kJ kg·ºC' noting that most of the thermal energy is retained in the short time of the discharge, (c) Calculate the new resistance, assuming it is pure carbon, (d) Does this change in resistance seem significant?
Integrated Concepts A 160 − μ F capacitor charged to 450 V is discharged through a 31.2-k Ω resistor. (a) Find the time constant. (b) Calculate the temperature increase of the resistor, given that its mass is 2.50 g and its specific heat is 1 .67 kJ kg·ºC' noting that most of the thermal energy is retained in the short time of the discharge, (c) Calculate the new resistance, assuming it is pure carbon, (d) Does this change in resistance seem significant?
A
160
−
μ
F
capacitor charged to 450 V is discharged through a 31.2-k
Ω
resistor. (a) Find the time constant. (b) Calculate the temperature increase of the resistor, given that its mass is 2.50 g and its specific heat is
1
.67
kJ
kg·ºC'
noting that most of the thermal energy is retained in the short time of the discharge, (c) Calculate the new resistance, assuming it is pure carbon, (d) Does this change in resistance seem significant?
C01: Physical Quantities, Units and Measurements
10 A student uses a rule to measure a thin piece of wire.
wire
0 1
cm
2
3
4
5
5 6 7 8
9 10 11 12 13 14
15
(a) State two errors in the student's measurement of the length of wire.
[2]
The student records the length of the wire as 12.8 cm.
[E]
The student is asked to measure the thickness of the wire using a pencil and the
same rule. Suggest how this can be done as accurately as possible.
[4]
(b) The student finds out that the density of the wire is 2.7 g/cm³. Express 2.7 g/cm³ in
kg/m³.
[2]
to V emulov or worl?
гавтоха
[E11 The length of a sheet of plastic is measured using a 15 cm rule.
eq
8
5
Imm 1
2
سيلينا
3
3
5
7
8
10
11 12
13
14
L
ins
15
sem of beiupe
stipib e elun olfastq e riliw bei
inebulz A
H
com al Jari Inemundeni or ezoori (s)
re the
sheet of plastic
tion v
more
m
C01: Physical Quantities, Units and Measurements
8
The following shows a pencil.
(a)
pencil
sharpened
section
Describe how you would use a piece of string and a rule to determine the
circumference c of the unsharpened section of the pencil.
[3]
nd pupp
e
e E
(b)
The student's value for the circumference c is 2.5 cm.
Suggest a source of error in determining the circumference of the pencil.
[1]
ntit
ble
Ec
et
(c)
Show the volume V of the unsharpened section of the pencil is V = c²x
[3]
ΑΠ
55
sn
ar
2
72
C:
or
n/
el
D
a
7
9
(d)
Express the volume VE of the sharpened section of the pencil in terms of c and y.
pilasi to leeries to rignal on [3]
State any assumptions made. lau besser
A student is required to measure the thickness of a ream of 500 sheets of A4 size paper.
He is supplied with a plastic rule, a digital micrometer screw gauge and a pair of digital
calipers.
(a) Choose the instrument that is most suitable to measure the thickness of the ream of
paper. Give two…
5
C01: Physical Quantities, Units and Measurements
4
Complete the table by stating a suitable instrument for obtaining each of the following
lengths to be measured. (6)
Length to be
measured
(a)
12.0 cm
(b)
8.880 mm
(c)
4.440 cm
(d)
(e)
internal diameter of a
test tubes bas
thickness of a wire
(f)
height of a bedroom
Suitable Instrument
5
Fill in the blanks by making estimates of each of the following quantities.
[5]
(a)
The thickness of a sheet of paper =
mm
(b)
The time for one heartbeat =
(c)
The mass of 500 cm3 of water =
S
g
(d)
The height of a 4-year-old
=
3
(e)
The average human reaction time
S
hoda
6 A student has a stack of 20 identical coins. The following diagram shows the student
measuring the height of the stack using a rule.uis en
cm 15.
10
7
eye
(6)
ream of
(3)
emuntani na mBM
(0)
5.
stack of
20 coins
0
(b)
With his eye at the position shown, the student's measurement of the height of the stack is 6.8
cm.
(a)
Suggest two reasons why the student's measurement is…
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