Physics ix kpk board

1. Physics Class IX ( 2018 ) Unit 01 Physical quantities and Measurement
Ex: Numerical
Q1 (a) (b) Sol
Sol:GivenMass= 10-21
kg Distance = 3.0 × 1018
m
Mass = 10-18
× 10-3
kg Distance = 3.0 exameter
Mass = 10-18
× 10--3
×103
gram Distance = 3.0 em
Mass = 10-18
gram
Mass = 1attogram= 1ag
(c)
Sol:Distance = 149.6 MKm
Distance = 149.6 × 106
× 103
m = 149.6 × 109
m
Distance = 149.6 Gm (because G= Giga = 109
)
Q2. Sol:Giventhat 1 angstrom = 10-10
m
1angsrom = 10-1
× 10-9
m = 10-1
nano metre
1 angstrom = 10-1
nm OR 1 angstrom= 0.1 nm
(b) For femto= 10-15
We write 10-10
= 105
× 10-15
Now 1 angstrom= 10-10
m= 105
× 10-15
m
But 1 femto= 10-15
Therefore, 1 angstrom= 105
femtometre =105
fm
( c ) Again 1 angstrom= 10-10
OR 10-10
m = 1angstrom

2. Physics Class IX ( 2018 ) Unit 01 Physical quantities and Measurement
Ex: Numerical
Then 1m = 1010
angstrom
Q3
Sol: speedof light= C = 299,792,458 m/s
In Scientificnotationthe above value
Speed = C = 2.99792458 ×108
m/s
(a) Nowspeedof light upto 5-Significantfigures,forbyroundingthe numbers (4,5,8) by rounding
method, we get speed=C= 2.99792 ×108
m/s
(b) Speed of lightupto 3-significantfigures, we onlykeepthe lastthree digits.
Speed= C = 2.998× 108
m/s= 3.00× 108
m/s