Making measurements
● Mass
○ Amount of matter present in an object
○ Measured by top pan balance or beam balance
● Weight
○ The amount of gravitational pull on an object
○ Mass x gravity (10g on Earth)
○ Measured by spring balance or newton meter
● Volume
○ Amount of space occupied by an object
● Density
○ It is mass per unit volume
○ Mass/Volume
○ Water = 1000 kg/m3
● Vernier Calliper
○ Method
■ Close the callipers so that the jaws touch lightly but on the sides of the object
being measured
■ Look at the zero on the vernier scale. Read the main scale just to the left of the
zero. This tells you the length in millimetres
■ Now look at the vernier scale. Find the point where one of its markings is exactly
aligned with one of the markings on the main scale. Read the value on the vernier
scale. This tells you the fraction of a millimetre that you must add to the main scale
reading
MSR= Main scale reading
VSR= Vernier scale reading
MSR= where first point of VSR is
VSR= where VSR and MSR point meet
● Micrometer screw gauge
○ Method
■ Turn the barrel until the jaws just tighten on the object. Using the friction clutch
ensures just the right pressure
■ Read the main scale to the nearest .5 mm
■ Read additional fraction of a millimeter from the fractional scale
● Zero Error
○ Negative zero error
■ Zero is over
■ Add from total value
○ Positive zero error
■ Zero is under
■ Subtract from total value
● Density of an irregularly shaped object that floats
○ Find mass(m) of the object with the help of beam balance and note it down
○ Pour water into graduated cylinder and record the volume of water(Vw)
○ Tie sinker with a thread and lower it into the container. Record new volume(V1)
○ Attach the sinker to the object with a thread and lower both into the container. Record
new volume(V2)
○ Volume of sinker = V1 - Vw
○ Volume of sinker and object = V2 - Vw
○ Volume of object = (V2 - Vw) - (V1 -Vw)
= V2 - V1
● Types of clocks
○ Digital clock
■ It gives direct reading of time in numerals.
■ Eg. 23.45 sec
○ Analogue clock
■ Traditional clock whose hands move around the clock face. Find time by looking at
where the hands are pointing to.
● An oscillation is the repetitive movement of an object
● Time taken to make one complete oscillation is called the period of oscillation
● Amplitude is the maximum displacement of a pendulum from its mean position
● Time period(T) = 2
π 𝑙/𝑔
Unit
Value
Giga(G)
10
9
Mega(M)
10
6
Kilo(k)
10
3
Deci(d)
10
-1
Centi(c)
10
–2
Milli(m)
10
–3
Micro(mew/µ)
10
–6
Nano(n)
10
–9
1 litre
1000ml
1litre
1000 cm3
1ml
1 cm3
