Previous Year Paper year:2013 : ICSE-X-Physics

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ICSE-X-Physics

Previous Year Paper year:2013

with Solutions - page 4

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#4-d-i
can cause severe genetical disorders.
Ans : Gamma radiations

#4-d-ii
are deflected by an electric field?
Ans : α and β radiations.

#4-e
A radioactive nucleus undergoes a series of decays according to the sequence
$$\ce{X->[\beta] X_1 ->[\alpha] X_2 ->[\alpha] X_3}$$
If the mass number and atomic number of ``X_3`` are 172 and 69 respectively, what is the mass
number and atomic number of X?
Ans :
Mass number of X = 180
Atomic number of X = 72

# [40]
Section : II

#5 [10]

#5-a

#5-a-i
With reference to their direction of action, how does a centripetal force differ
from a centrifugal force?
Ans : Centripetal force directed towards the centre of circle while centrifugal force is opposite to centripetal force.

#5-a-ii
State the Principle of conservation of energy.
Ans : Principle of Conservation of Energy : Energy can neither be created nor destroyed. It convert from one form to other form.

#5-a-iii
Name the form of energy which a body may possess even when it is not in
motion.
Ans : Potential energy.

#5-b
A coolie is pushing a box weighing 1500 N up an inclined plane 7.5 m long on to a
platform, 2.5 m above the ground.

#5-b-i
Calculate the mechanical advantage of the inclined plane.
Ans : Given: l = 7.5 m, h = 2.5 m.

#5-b-ii
Calculate the effort applied by the coolie.
Ans :

#5-b-iii
In a actual practice, the collie needs to apply more effort than what is calculated.
Give one reason why you think the coolie needs to apply more effort.
Ans : In actual practice, due to some friction between the plane and the bottom face of the body which is pulled over it, the effort needed is certainly more than L sin θ , so the mechanical advantage is always less than l/h, hence, efficiency is less than 1.

#5-c
A block and tackle system of pulleys has a velocity ratio 4.

#5-c-i
Draw a labelled diagram of the system indicating clearly the points of application
and directions of load and effort.
Ans : See diagram alongside.