Page 4 - ECAT Past Paper 2006

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Work done= Fd cos180* :. Cos180*= -1
Work done= -Fd (Answer)
Q.8 Solar cells are thin wafers made from:
A) Boron B) Silicon (Correct)
C) Germanium D) Cadmium
-Self Explanatory.
Q.9 The dimension of angular velocity is:
-1
-2
A) LT B) LT
-1
-2
C) T (Correct) D) T
Explanation:
As we know that:
w=∆θ/∆t
As unit of angular velocity is rad/sec so its dimension is T .
-1
Q.10 Ball pens function on the principle of:
A) Viscosity B) Boyle’s Law
C) Gravitational Law D) Surface Tension (Correct)
-Self Explanatory.
Q.11 If temperature rises , the coefficient of viscosity of a liquid?
A) Decreases (Correct) B) increases
C) remains same D) increases for some liquids and decreases
for others
Explanation:
Viscosities of liquids and solids decrease with increment in temperature while viscosity of
gases increase with the increasing of temperature.
Q.12 The displacement of particle executing SHM is half of its magnitude. The fraction of its
K.E will be:
A) 2/3 B) ¼
C) 1/3 D) ½
E) None of these (Correct)
Explanation:
According to given condition:
x= ½ xo
As we know that:
2
K.E= ½ mv
As we also know that

v=wxo√ −

( )
√
v=wxo −

v=wxo √ −

v=wxo√ −

√
v=wxo

As w= √

√

K.E= ½ m (√ xo )

2
K.E= ½ kxo (3/4)
K.E= 3/8 kxo (Answer)
2
Q.13 Which of the following has longest wavelength?