# Physics 2015 | Study Mode

Question 31
A
B
infrared rays
C
Visible light
D
Gamma rays
##### Explanation
Infrared rays are easily detected by special photographic films and it can be used for taking picture in haze

Question 32
A
2 sec
B
3 sec
C
4sec
D
3.2sec
##### Explanation
From S = ut + gt2

u = 0ms-1

50 = (0 t) + (10)(t2)

50 = 5.0t2

t2 =50/5

t = 10

t = 3.2sec

Question 33
A
0.11kg
B
0.12kg
C
0.13kg
D
0.14kg
##### Explanation
Heat capacity (o) = mass (kg) specific heat of a substance (C2)

i.e Q = MC

where Q = 40 J/L, m = ?(380 J/Kgk)

40 = m 380

m = 0.11kg (Approx)

Question 34
A
2sec
B
3sec
C
35sec
D
2.4sec
##### Explanation
Using the equation

S = ut + gt2

H = s = 20m, t = ?

G =10m/s2, u = 0m/s

20 = 0 t 10 t

20 = 5t

i.e 5t2 = 20

t = 20/5 = 4

t = 4 (squaring both sides)

t2 = 4

= 2sec

t = 2sec

Question 35
A
2 : 5
B
1 : 5
C
5 : 1
D
3 : 1
##### Explanation
Velocity Ratio (V.R) = distance moved by the effort (x) distance moved by the load (y)

i.e. V.R = x/y

v. R = 5, x/y = ?

i.e x/y = 5/1; , where x = 5, y = 1

x : y = 5 : 1

Question 36
A
4:01
B
1:04
C
5:01
D
2:01
##### Explanation
Mechanical advantage (M.A) of a machine is the ratio of its load to effort

Mathematically

In symbol M.A = L/E

Note:Mechanical (advantages has no S.I unit)

If M.A = 4 then,

L/E = 4/1

The ratio of load to effort = 4 : 1 respectively

Question 37
A
Mercury thermometer
B
gas thermometer
C
clinical thermometer
D
alcohol thermometer
##### Explanation
A gas thermometers are more besting use to achieve an accurate temperature than others, such as liquid in glass thermometers such as mercury, clinical and alcohol thermometer

Question 38
A
Bothe light and heavy subject reach the ground at the same time
B
he light object get to the ground first before the heavy object
C
he heavy object to the ground first before the light object
D
None get to the ground first
##### Explanation
(Neglect of Air resistance)

Note: Both objects reach the ground at the same time

Question 39
A
B
C
D
##### Explanation
M= 3kg, r = 0.7m, v = 2m/s

v = wr

w = angular velocity

r = radius in an tangential circular

v = speed of an object

W = V/ = 2/ 0.7 = 2.85

W = 2.853rads1 (total interest whole number)

Question 40
A
Telescope
B
sextant
C
microscope
D
periscope
##### Explanation
Microscope is used for nearby object

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