# Physics 2015 | Study Mode

Question 61
A
B
Mass
C
Work
D
Time
##### Explanation

Temperature gradient(Tg) = DT L = T2 T1 L

i.e it is the ratio of an increment in temperature to the length

Hence, Temperature gradient (Tg) has defined direction alongside with magnitude

And it is a vector quantity

Mass, work & Time are scalar quantity

Question 62
A
Efficiency of transformer = (secondary coil primary coil) 100%
B
Efficiency of transformer = (mechanical advantage velocity ratio) 100%
C
Efficiency of a transformer = (Number of turns in the secondary coil Number of turns in the primary coil) 100%
D
Efficiency of a transformer = (power developed in the secondary coil power supplied to the primary coil) 100%
##### Explanation
Efficiency of a transformer = (power developed in the secondary coil power supplied to the primary coil) 100%

Question 63
A
Have high boiling points
B
have low boiling points
C
have high densities
D
have high melting points
##### Explanation
Volatile liquids (i.e. Ammonia or Freon) are usually have low boiling point

Question 64
A
2 m/s
B
4 m/s
C
12 m/s
D
14 m/s
##### Explanation
d = y, s = 6 m/s (The Man & Plane Mirror)

d y, s = (5 6) m/s (The Man and Image)

d2 s1 = d2 s2, y 6 = 2y s + 6

Y (s + 6) = 2y 6

s + 6 = 12

So = 12 6 = 6

Since S + 6 = 0

Then, S = 6 (substitute the value of S i.e S = 6)

Into S + 6 = 0

So = S + 6 = 6 + 6 = 12 m/s

S = 12 m/s

Question 65
A
Voltmeter
B
Meter rule
C
Galvanometer
D
Potentiometer
##### Explanation
Voltmeter: an instrument for measuring electric potential in volts

Galvanometer: it is a device used to indicate direction of a small electric current

Potentiometer: is a device for measuring or comparing e.m.fs of cells

Meter rule: measuring a distance at different points

Question 66
A
I only
B
II and IV only
C
II only
D
III only
##### Explanation
In an inelastic collision, linear momentum is conserved and energy is decreased

Momentum and kinetic energy are conserved in elastic collision

Question 67
A
III only
B
II & III only
C
I only
D
II, III & IV only
##### Explanation
Simple pendulum does not depend on thermal expansion

Five alarms, Thermostat and Bimetallic thermometer are application of thermal expansion of solid

Question 68
A
27C to 43C
B
30C to 40
C
98.4C only
D
Between 35C to 37C
##### Explanation
The range of temperature is between 35C and 43C but for normal temperature of human body is between the range of 35C to 37C respectively

Question 69
A
force
B
Impulse
C
Energy
D
Inertia
##### Explanation
Inertia: the property of a body that resists any change to its uniform motion, equivalent to its mass

Question 70
A
Inelastic collision
B
Elastic collision
C
Explosion
D
Spacecraft
##### Explanation
Momentum and kinetic energy are conversed in elastic collision

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