# Physics (2018) | Study Mode

Question 61
A
0.33
B
0.50
C
0.67
D
0.90
##### Explanation

Volume of liquid displaced

= $$\frac{2}{3}$$(0.5)$$^3$$

Mass of liquid displaced = mass of floating cube = 75kg

Density of liquid = $$\frac{mass}{volume}$$

= $$\frac{75}{(\frac{7}{3(0.5)})}$$ 3

= 0.9 103kgm$$^{-3}$$

R.D of liquid = $$\frac{(0.9 )}{(1.0)}$$ 103

= 0.9

Question 62
A
330.0m
B
335.4m
C
660.0m
D
670.8m
##### Explanation

Recall V = F lambda
= 260 1.29
= 335.4ms$$^{-1}$$

Question 63
A
Low density
B
Hypothermal conductivity
C
Low electrical resistivity
D
Low melting point
##### Explanation

Fuse wires have a low melting point so that if a huge amount of current is passed through it to any appliance than that wire would melt and stop the appliance from getting damaged by not letting the current pass any further.

Question 64
A
60V
B
150V
C
225V
D
360V
##### Explanation

P = 40W

R = 90W

V = ?

P = $$\frac{V^2}{R}$$

V$$^2$$ = PR = 40 x 90

V$$^2$$ = 3000

V = 3600

V = 60N

Question 65
A
Mercury is a metal
B
The cohesive force between its molecules is greater than the adhesive force between mercury and glass molecules
C
The cohesive force between its molecules is less than the adhesive force between mercury and glass molecules
D
The viscosity of mercury is height
##### Explanation

In case of small drops of mercury, the gravitational potential energy is negligible in comparison to the potential energy due to surface tension.Consequently, to keep the drop in equilibrium, the mercury drops surface tends to contract so that its surface area will be the least for a sphere and the drops will be spherical.

But in the case of bigger drops of mercury, the potential energy due to gravity is predominant over the potential energy due to surface tension.Consequently, to keep equilibrium , the mercury drop tends to assume minimum potential energy as possible, the drop becomes oval in shape and lower center of gravity.

Question 66
A
33$$^o$$c
B
40$$^o$$c
C
25$$^o$$c
D
10$$^o$$c
##### Explanation

Water 1 => M = 150g = 0.15kg,

$$_2$$ = 60$$^o$$C; $$_1$$ =

Q$$_1$$ = MC ($$_2$$ $$_1$$)

= 0.15C (60 - )

Water 2 => M = 300g = 0.3kg

1 = 20$$^o$$C, $$_2$$ =

Q2 = MC ($$_2$$ $$_1$$)

= 0.3C ( 20)

Combining Q1 and Q2

0.15C (60 - ) = 0.3C ( 20)

9 0.15 = 0.3 6

0.3 + 0.15 = 9 + 6

0.45 = 15

= 33.33$$^o$$C

Question 67
A
Transitional Motion
B
Rotational Motion
C
Brownian Motion
D
Oscillatory Motion
##### Explanation

Brownian motion, also called Brownian movement, any of various physical phenomena in which some quantity is constantly undergoing small, random fluctuations.
If a number of particles subject to Brownian motion are present in a given medium and there is no preferred direction for the random oscillations, then over a period of time the particles will tend to be spread evenly throughout the medium.

Question 68
A
thermionic emission
B
nuclear fission
C
thermonuclear fusion
D
photoelectric emission
##### Explanation

Thermionic emission: thermally induced flow of charge
Nuclear fission: nuclear reaction or a radioactive decay process
Photoelectric emission: emission of electrons or other free carriers when light shines on a material

Question 69
A
X ray
B
Y ray
C
particles
D
neutron
##### Explanation

Y Ray is a penetrating electro-magnetic radiation.
particle is produced in the process of alpha decay.
Neutron is a sub-atomic particle.

Question 70
A
Convection
B