# Physics 2015 | Study Mode

Question 21
A
318K
B
250K
C
184K
D
120K
##### Explanation
Note: T = 273 +

= 45

T = 273 + 45

= 318K

Question 22
A
Fall freely from the earths gravitational field
B
Is walking on the planet
C
In between the sun and the earth
D
Holding anything in space is negative
##### Explanation
Weightlessness: The state of being free from the effects of gravity. (zero gravity)

Question 23
A
34m/s
B
3 106m/s
C
3 108m/s
D
3 10-8m/s
##### Explanation
A radio waves is an electromagnetic waves which travels with a constant velocity of 3 108m/s

Question 24
A
0.27g / liters
B
0.25g / liters
C
1.7g / liters
D
0.15g / liters
##### Explanation

$$\theta1 = 35C T1 = 273 + = 73 + 35 = 308k P1 = 5$$atm

d1 = 0.600g/ litre

2 = 350C, T2 = 2 + 3 +

= 273 + 350 = 623k, d2 = ?

P2 = 7atm

T a P a 1/d = TPK/d (where k is a constant)

Tp1 d1 = T1P2 d2, [(308 5) 0.600]

= (623 7) d2

d2 = (623 7 0.600) (308 5)

= 2616.6 1540

= 1.69g / litresd2 = 1.69g / litres

d2 = 1.70g / litres (Approx.)

Question 25
A
Compression and Rarefaction
B
Comparison and Explosion
C
Reflection only
D
Refraction only
##### Explanation
The vibrating particles behave like a spiral spring with a series of compression region and spaceout region.

Question 26
A
1, 2, 1
B
1, 2, 2
C
1, 1, 2
D
2, 2, 1
##### Explanation
Work (w) = Force (f) Distance (d)

Note: f = ma = mass acceleration

= mass acceleration distance

= kg ms2 m

= kg m2 52

(Note: the dimension of kg = M, M = L & S = T)

Work = ML2 T2 = Ma Lb Tc

i.e. Ma Lb Tc = as 1, b = 2, c = 2

The value of a, band c = 1, 2, 2

Question 27
A
Electromagnetic devices
B
Magnetic relay device
C
None at all
D
Sextant
##### Explanation
Magnetic relay device :is the device that controls a circuit (i.e one circuit )if a current in the second circuit is large or dangerous

Question 28
A
Conduction
B
Convection
C
D
Expansion
##### Explanation
Conduction, conveying of heat or electricity through a material medium is required

Question 29
A
Thermometer
B
Measuring cylinder
C
Calorimeter
D
Meter rule
##### Explanation
Calorimeter is an apparatuses used for measuring the heat (Q) generated or absorbed by change of phase (state) or other physical change

Question 30
A
N W when suspended freely
B
NS when suspended freely
C
S E when suspended freely
D
SW when suspended freely
##### Explanation
Lodestone is a natural magnet it points approximate at N S when suspended freely

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