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## Class 9 Physics Solved Paper 2018

Class 9 Physics Solved Paper 2018 for Federal Board is available in this post. You can see more FBISE solved past papers of class 9 on our website.

## Class 9 Physics Solved Paper 2018

### Class 9 Physics Solved Paper 2018Section B

#### Q2.

(i) On closing the stud and spindle of a screw gauge, the zero of the circular scale is behind the index line and the 8th division of the circular scale coincides with the index line. There are 50 divisions on the circular scale and the distance between two consecutive threads on the spindle is 0.5mm. Find its zero error and zero correction.

Sol: Number of divisions on the circular scale = 50
Pitch of the screw gauge = 0.5 mm

On closing the stud and spindle of a screw gauge:

Main scale reading             =          0 mm
Circular scale reading        =          8 x 0.01 mm
=          0.08 mm

Zero error of the screw gauge  =          (0+ 0.08) mm
=          + 0.08 mm

Zero Correction of the screw gauge   = – 0.08 mm

##### (ii)    Define Atomic Physics and Nuclear Physics.

Excluded from Syllabus for Annual Exam 2021

##### (iii)    A cyclist completes half round of a circular track of diameter 636 m in 1.5 minutes. Find his velocity.

Sol.   Diameter of circular track = D = 636 m
Radius of circular track = r = D/2 = 636 / 2 = 318 m
Time taken   t = 1.5 min = 1.5 × 60 = 90 s
Distance covered      S = π × radius
= 3.14 × 318 m = 999 m
Displacement            d = 2 r
= 2 × 318 m = 636 m

##### (iv)   Define Inertia. Describe the factor on which it depends.

Ans.Inertia
Definition
It is a property of a body due to which it resists any change in its state of rest or motion.
Factors on which Inertia Depends
Inertia depends on the mass of a body. Greater is the mass of a body greater is its inertia.

##### (v)   How much time is required to change 22 Ns momentum by a force of 20 N?

Sol.     Change in momentum = Pf – Pi = 22 Ns
Force = F = 20 N
Time = t =?
We know that

##### (vi)   Can a small child play with a fat child on the sea-saw? Briefly explain now?

Excluded from Syllabus for Annual Exam 2021

##### (vii)   On the surface of the earth, the weight of a boy is 400N but on a mountain peak, his weight is 360N. Calculate the value of ‘g’ on the mountain peak.

Sol.     Weight of boy on Earth = we = 400 N
Weight of boy on mountain peak = wm = 360 N
Value of g on Earth = ge = 10 ms-1
Value of g on mountain peak = gm =?

##### (viii)    State the law of gravitation.
Ans.    Law of Gravitation
This law states that “everybody in this universe attracts every other body with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers”.  

##### (ix)   Make a flow diagram of energy conversion for a hydroelectric power station.

Excluded from Syllabus for Annual Exam 2021

(x)    Describe Hooke’s Law.

Ans. Hooke’s Law
This law states that within the elastic limit, the strain produced in a body is directly proportional to the stress applied on it.

##### (xi)   Describe the factors on which upthrust of a liquid depends.

Ans.    Upthrust is given by the formula
F = V ρ g
Where
V = Volume of liquid displaced by the object
ρ = Density of liquid
Hence upthrust of a liquid depends upon the density of a liquid and the volume of liquid displaced
by an object.

Excluded from Syllabus for Annual Exam 2021

##### (xiv)    a.    Why does temperature of a solid substance not increase during its fusion?

Excluded from Syllabus for Annual Exam 2021

##### b.    Differentiate between boiling and condensation.

Excluded from Syllabus for Annual Exam 2021

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