NEET 2019 Paper with Detailed Solutions - Physics | Additional Study Material for NEET PDF Download

 Page 1


1
FINAL NEET(UG)–2019 EXAMINATION
(Held On Sunday 05
th
 MAY , 2019)
PHYSICS TEST PAPER WITH ANSWER & SOLUTION
46. In which of the following processes, heat is neither absorbed nor released by a system ?
(1) isothermal (2) adiabatic (3) isobaric (4) isochoric
Ans. (2)
Sol. Adiabatic process
DQ = 0
47. Increase in temperature of a gas filled in a container would lead to :
(1) increase in its mass (2) increase in its kinetic energy
(3) decrease in its pressure (4) decrease in intermolecular distance
Ans. (2)
Sol. KE µ Temperature
As temperature increases KE also increases
48. The total energy of an electron in an atom in an orbit is ?3.4 eV . Its kinetic and potential energies are, respectively:
(1) ?3.4 eV, ?3.4 eV (2) ?3.4 eV, ?6.8 eV
(3) 3.4 eV, ?6.8 eV (4) 3.4 eV, 3.4 eV
Ans. (3)
Sol. TE = ?3.4 eV
KE = ?T.E PE = 2T.E
Þ KE = +3.4 eV Þ PE = ?6.8 eV
49.
R
R
+6V
A1
B1
0
LED (Y)
0
The correct Boolean operation represented by the circuit diagram drawn is :
(1) AND (2) OR (3) NAND (4) NOR
Ans. (3)
Sol. A BY
0 01
0 11
1 01
1 10
\ It is a NAND Gate
Page 2


1
FINAL NEET(UG)–2019 EXAMINATION
(Held On Sunday 05
th
 MAY , 2019)
PHYSICS TEST PAPER WITH ANSWER & SOLUTION
46. In which of the following processes, heat is neither absorbed nor released by a system ?
(1) isothermal (2) adiabatic (3) isobaric (4) isochoric
Ans. (2)
Sol. Adiabatic process
DQ = 0
47. Increase in temperature of a gas filled in a container would lead to :
(1) increase in its mass (2) increase in its kinetic energy
(3) decrease in its pressure (4) decrease in intermolecular distance
Ans. (2)
Sol. KE µ Temperature
As temperature increases KE also increases
48. The total energy of an electron in an atom in an orbit is ?3.4 eV . Its kinetic and potential energies are, respectively:
(1) ?3.4 eV, ?3.4 eV (2) ?3.4 eV, ?6.8 eV
(3) 3.4 eV, ?6.8 eV (4) 3.4 eV, 3.4 eV
Ans. (3)
Sol. TE = ?3.4 eV
KE = ?T.E PE = 2T.E
Þ KE = +3.4 eV Þ PE = ?6.8 eV
49.
R
R
+6V
A1
B1
0
LED (Y)
0
The correct Boolean operation represented by the circuit diagram drawn is :
(1) AND (2) OR (3) NAND (4) NOR
Ans. (3)
Sol. A BY
0 01
0 11
1 01
1 10
\ It is a NAND Gate
2
 
50. A block of mass 10 kg is in contact against the inner wall of a hollow cylindrical drum of radius 1 m. The coefficient
of friction between the block and the inner wall of the cylinder is 0.1. The minimum angular velocity needed
for the cylinder to keep the block stationary when the cylinder is vertical and rotating about its axis, will be :
(g = 10 m/s
2
)
(1) 
10
 rad/s (2) 
p
10
2
 rad/s (3) 10 rad/s (4) 10p rad/s
Ans. (3)
Sol. f
L
 = mN =
 
mmrw
2
f
s
 = mg              
f
s
w
N
mg
As f
s
 £ f
L
Þ mg £ mmrw
2
Þ 
w³
m
g
r
Þ w
min
  = 10 rad/s
51. Body A of mass 4m moving with speed u collides with another body B of mass 2m, at rest. The collision is head
on and elastic in nature. After the collision the fraction of energy lost by the colliding body A is :
(1) 
1
9
(2) 
8
9
(3) 
4
9
(4) 
5
9
Ans. (2)
Sol.
4m
A
u
2m
B
rest
4m
v
1 2m
v
2
-
= ==
+
1
4m 2m 2mu u
vu
4m 2m 6m 3
Fraction of energy lost = 
æö
-
ç÷
èø
2
2
2
1 1u
(4m)u (4m)
2 23
1
(4m)u
2
           = -=
18
1
99
52. The speed of a swimmer in still water is 20 m/s. The speed of river water is 10 m/s and is flowing due east.
If he is standing on the south bank and wishes to cross the river along the shortest path, the angle at which
he should make his strokes w.r.t. north is given by :
(1) 30° west (2) 0° (3) 60° west (4) 45° west
Ans. (1)
Sol. v = 20 m/s
u = 10 m/s
u
v
q
q= ==
u 101
sin
v 202
Þq = 30° west
Page 3


1
FINAL NEET(UG)–2019 EXAMINATION
(Held On Sunday 05
th
 MAY , 2019)
PHYSICS TEST PAPER WITH ANSWER & SOLUTION
46. In which of the following processes, heat is neither absorbed nor released by a system ?
(1) isothermal (2) adiabatic (3) isobaric (4) isochoric
Ans. (2)
Sol. Adiabatic process
DQ = 0
47. Increase in temperature of a gas filled in a container would lead to :
(1) increase in its mass (2) increase in its kinetic energy
(3) decrease in its pressure (4) decrease in intermolecular distance
Ans. (2)
Sol. KE µ Temperature
As temperature increases KE also increases
48. The total energy of an electron in an atom in an orbit is ?3.4 eV . Its kinetic and potential energies are, respectively:
(1) ?3.4 eV, ?3.4 eV (2) ?3.4 eV, ?6.8 eV
(3) 3.4 eV, ?6.8 eV (4) 3.4 eV, 3.4 eV
Ans. (3)
Sol. TE = ?3.4 eV
KE = ?T.E PE = 2T.E
Þ KE = +3.4 eV Þ PE = ?6.8 eV
49.
R
R
+6V
A1
B1
0
LED (Y)
0
The correct Boolean operation represented by the circuit diagram drawn is :
(1) AND (2) OR (3) NAND (4) NOR
Ans. (3)
Sol. A BY
0 01
0 11
1 01
1 10
\ It is a NAND Gate
2
 
50. A block of mass 10 kg is in contact against the inner wall of a hollow cylindrical drum of radius 1 m. The coefficient
of friction between the block and the inner wall of the cylinder is 0.1. The minimum angular velocity needed
for the cylinder to keep the block stationary when the cylinder is vertical and rotating about its axis, will be :
(g = 10 m/s
2
)
(1) 
10
 rad/s (2) 
p
10
2
 rad/s (3) 10 rad/s (4) 10p rad/s
Ans. (3)
Sol. f
L
 = mN =
 
mmrw
2
f
s
 = mg              
f
s
w
N
mg
As f
s
 £ f
L
Þ mg £ mmrw
2
Þ 
w³
m
g
r
Þ w
min
  = 10 rad/s
51. Body A of mass 4m moving with speed u collides with another body B of mass 2m, at rest. The collision is head
on and elastic in nature. After the collision the fraction of energy lost by the colliding body A is :
(1) 
1
9
(2) 
8
9
(3) 
4
9
(4) 
5
9
Ans. (2)
Sol.
4m
A
u
2m
B
rest
4m
v
1 2m
v
2
-
= ==
+
1
4m 2m 2mu u
vu
4m 2m 6m 3
Fraction of energy lost = 
æö
-
ç÷
èø
2
2
2
1 1u
(4m)u (4m)
2 23
1
(4m)u
2
           = -=
18
1
99
52. The speed of a swimmer in still water is 20 m/s. The speed of river water is 10 m/s and is flowing due east.
If he is standing on the south bank and wishes to cross the river along the shortest path, the angle at which
he should make his strokes w.r.t. north is given by :
(1) 30° west (2) 0° (3) 60° west (4) 45° west
Ans. (1)
Sol. v = 20 m/s
u = 10 m/s
u
v
q
q= ==
u 101
sin
v 202
Þq = 30° west
3
53. A mass m is attached to a thin wire and whirled in a vertical circle. The wire is most likely to break when :
(1) the mass is at the highest point (2) the wire is horizontal
(3) the mass is at the lowest point (4) inclined at an angle of 60° from vertical
Ans. (3)
Sol. T ? mg cos q = 
2
mv
R
q
m
T
mg
T will be maximum when q = 0°,
When mass is at lowest point.
54. The displacement of a particle executing simple harmonic motion is given by
y = A
0
 + Asinwt + Bcoswt.
Then the amplitude of its oscillation is given by :
(1) 
++
22
0
A AB
(2) 
+
22
AB
(3) ++
22
0
A (A B) (4) A + B
Ans. (2)
Sol. y = A
0
 + A sin wt + B cos wt
y = A
0
 +
22
AB + sin (wt + f)
A
0
 is mean position, and 
22
AB + is amplitude
55. A 800 turn coil of effective area 0.05 m
2
 is kept perpendicular to a magnetic field 5 × 10
?5
 T. When the plane
of the coil is rotated by 90° around any of its coplanar axis in 0.1 s, the emf induced in the coil will be :
(1) 2 V (2) 0.2 V (3) 2 × 10
?3 
V (4) 0.02 V
Ans. (4)
Sol. Given
N = 800, A = 0.05 m
2
, B = 5 × 10
?5
 T
Dt = 0.15 s
As e = 
f-f-
=-
DD
fi
( ) (0 NBA)
?
tt
  = 
-
´ ´ ´´
?52
800 5 10 5 10
0.1
 = 0.02 V
56. Average velocity of a particle executing SHM in one complete vibration is :
(1) 
w A
2
(2) Aw (3) 
w
2
A
2
(4) Zero
Ans. (4)
Sol. Displacement = zero in one complete oscillation
Þ Average velocity = =
Displacement
0
T
Page 4


1
FINAL NEET(UG)–2019 EXAMINATION
(Held On Sunday 05
th
 MAY , 2019)
PHYSICS TEST PAPER WITH ANSWER & SOLUTION
46. In which of the following processes, heat is neither absorbed nor released by a system ?
(1) isothermal (2) adiabatic (3) isobaric (4) isochoric
Ans. (2)
Sol. Adiabatic process
DQ = 0
47. Increase in temperature of a gas filled in a container would lead to :
(1) increase in its mass (2) increase in its kinetic energy
(3) decrease in its pressure (4) decrease in intermolecular distance
Ans. (2)
Sol. KE µ Temperature
As temperature increases KE also increases
48. The total energy of an electron in an atom in an orbit is ?3.4 eV . Its kinetic and potential energies are, respectively:
(1) ?3.4 eV, ?3.4 eV (2) ?3.4 eV, ?6.8 eV
(3) 3.4 eV, ?6.8 eV (4) 3.4 eV, 3.4 eV
Ans. (3)
Sol. TE = ?3.4 eV
KE = ?T.E PE = 2T.E
Þ KE = +3.4 eV Þ PE = ?6.8 eV
49.
R
R
+6V
A1
B1
0
LED (Y)
0
The correct Boolean operation represented by the circuit diagram drawn is :
(1) AND (2) OR (3) NAND (4) NOR
Ans. (3)
Sol. A BY
0 01
0 11
1 01
1 10
\ It is a NAND Gate
2
 
50. A block of mass 10 kg is in contact against the inner wall of a hollow cylindrical drum of radius 1 m. The coefficient
of friction between the block and the inner wall of the cylinder is 0.1. The minimum angular velocity needed
for the cylinder to keep the block stationary when the cylinder is vertical and rotating about its axis, will be :
(g = 10 m/s
2
)
(1) 
10
 rad/s (2) 
p
10
2
 rad/s (3) 10 rad/s (4) 10p rad/s
Ans. (3)
Sol. f
L
 = mN =
 
mmrw
2
f
s
 = mg              
f
s
w
N
mg
As f
s
 £ f
L
Þ mg £ mmrw
2
Þ 
w³
m
g
r
Þ w
min
  = 10 rad/s
51. Body A of mass 4m moving with speed u collides with another body B of mass 2m, at rest. The collision is head
on and elastic in nature. After the collision the fraction of energy lost by the colliding body A is :
(1) 
1
9
(2) 
8
9
(3) 
4
9
(4) 
5
9
Ans. (2)
Sol.
4m
A
u
2m
B
rest
4m
v
1 2m
v
2
-
= ==
+
1
4m 2m 2mu u
vu
4m 2m 6m 3
Fraction of energy lost = 
æö
-
ç÷
èø
2
2
2
1 1u
(4m)u (4m)
2 23
1
(4m)u
2
           = -=
18
1
99
52. The speed of a swimmer in still water is 20 m/s. The speed of river water is 10 m/s and is flowing due east.
If he is standing on the south bank and wishes to cross the river along the shortest path, the angle at which
he should make his strokes w.r.t. north is given by :
(1) 30° west (2) 0° (3) 60° west (4) 45° west
Ans. (1)
Sol. v = 20 m/s
u = 10 m/s
u
v
q
q= ==
u 101
sin
v 202
Þq = 30° west
3
53. A mass m is attached to a thin wire and whirled in a vertical circle. The wire is most likely to break when :
(1) the mass is at the highest point (2) the wire is horizontal
(3) the mass is at the lowest point (4) inclined at an angle of 60° from vertical
Ans. (3)
Sol. T ? mg cos q = 
2
mv
R
q
m
T
mg
T will be maximum when q = 0°,
When mass is at lowest point.
54. The displacement of a particle executing simple harmonic motion is given by
y = A
0
 + Asinwt + Bcoswt.
Then the amplitude of its oscillation is given by :
(1) 
++
22
0
A AB
(2) 
+
22
AB
(3) ++
22
0
A (A B) (4) A + B
Ans. (2)
Sol. y = A
0
 + A sin wt + B cos wt
y = A
0
 +
22
AB + sin (wt + f)
A
0
 is mean position, and 
22
AB + is amplitude
55. A 800 turn coil of effective area 0.05 m
2
 is kept perpendicular to a magnetic field 5 × 10
?5
 T. When the plane
of the coil is rotated by 90° around any of its coplanar axis in 0.1 s, the emf induced in the coil will be :
(1) 2 V (2) 0.2 V (3) 2 × 10
?3 
V (4) 0.02 V
Ans. (4)
Sol. Given
N = 800, A = 0.05 m
2
, B = 5 × 10
?5
 T
Dt = 0.15 s
As e = 
f-f-
=-
DD
fi
( ) (0 NBA)
?
tt
  = 
-
´ ´ ´´
?52
800 5 10 5 10
0.1
 = 0.02 V
56. Average velocity of a particle executing SHM in one complete vibration is :
(1) 
w A
2
(2) Aw (3) 
w
2
A
2
(4) Zero
Ans. (4)
Sol. Displacement = zero in one complete oscillation
Þ Average velocity = =
Displacement
0
T
4
 
57. A soap bubble, having radius of 1 mm, is blown from a detergent solution having a surface tension of
2.5 × 10
?2
 N/m. The pressure inside the bubble equals at a point Z
0 
below the free surface of water in a container .
Taking g = 10 m/s
2
 density of water = 10
3
 kg/m
3
, the value of Z
0
 is :-
(1) 100 cm (2) 10 cm (3) 1 cm (4) 0.5 cm
Ans. (3)
Sol. P = P
0
 + rgZ
0
.........(i)
Also,  P = P
0
 + 
4T
R
.........(ii)
From (i) & (ii)
rgZ
0
 =
4T
R
\ Z
0
 = 
2
33
4T 4 2.5 10
gR 10 10 10
-
-
´´
=
r ´´
= 10
?2
 m = 1 cm
58. A copper rod of 88 cm and an aluminum rod of unknown length have their increase in length independent of
increase in temperature. The length of aluminum rod is : (a
Cu
 = 1.7 × 10
?5
 K
?1
 and a
Al
 = 2.2 × 10
?5
 K
?1
)
(1) 6.8 cm (2) 113.9 cm (3) 88 cm (4) 68 cm
Ans. (4)
Sol. At any temperature
(D l)
Cu 
= (Dl)
Al
l
1
a
1
DT = l
2
a
2
DT
88 × 1.7 × 10
?5
 = l
2
 × 2.2 × 10
?5
l
2
 = 68 cm
59. The unit of thermal conductivity is :
(1) J m K
?1
(2) J m
?1
 K
?1
(3) W m K
?1
(4) W m
?1
 K
?1
Ans. (4)
Sol.
dQ dT
(K)A
dt dx
=-
2
J kelvin
(K)m
sm
=
(K) = watt m
?1
 K
?1
60. When a block of mass M is suspended by a long wire of length L, the length of the wire become (L+l). The
elastic potential energy stored in the extended wire is :-
(1) Mgl (2) MgL (3) 
1
2
 Mgl (4) 
1
2
 MgL
Ans. (3)
Sol. U = 
1
2
(force)(elongation)
==
11
(Mg) Mg
22
ll
Page 5


1
FINAL NEET(UG)–2019 EXAMINATION
(Held On Sunday 05
th
 MAY , 2019)
PHYSICS TEST PAPER WITH ANSWER & SOLUTION
46. In which of the following processes, heat is neither absorbed nor released by a system ?
(1) isothermal (2) adiabatic (3) isobaric (4) isochoric
Ans. (2)
Sol. Adiabatic process
DQ = 0
47. Increase in temperature of a gas filled in a container would lead to :
(1) increase in its mass (2) increase in its kinetic energy
(3) decrease in its pressure (4) decrease in intermolecular distance
Ans. (2)
Sol. KE µ Temperature
As temperature increases KE also increases
48. The total energy of an electron in an atom in an orbit is ?3.4 eV . Its kinetic and potential energies are, respectively:
(1) ?3.4 eV, ?3.4 eV (2) ?3.4 eV, ?6.8 eV
(3) 3.4 eV, ?6.8 eV (4) 3.4 eV, 3.4 eV
Ans. (3)
Sol. TE = ?3.4 eV
KE = ?T.E PE = 2T.E
Þ KE = +3.4 eV Þ PE = ?6.8 eV
49.
R
R
+6V
A1
B1
0
LED (Y)
0
The correct Boolean operation represented by the circuit diagram drawn is :
(1) AND (2) OR (3) NAND (4) NOR
Ans. (3)
Sol. A BY
0 01
0 11
1 01
1 10
\ It is a NAND Gate
2
 
50. A block of mass 10 kg is in contact against the inner wall of a hollow cylindrical drum of radius 1 m. The coefficient
of friction between the block and the inner wall of the cylinder is 0.1. The minimum angular velocity needed
for the cylinder to keep the block stationary when the cylinder is vertical and rotating about its axis, will be :
(g = 10 m/s
2
)
(1) 
10
 rad/s (2) 
p
10
2
 rad/s (3) 10 rad/s (4) 10p rad/s
Ans. (3)
Sol. f
L
 = mN =
 
mmrw
2
f
s
 = mg              
f
s
w
N
mg
As f
s
 £ f
L
Þ mg £ mmrw
2
Þ 
w³
m
g
r
Þ w
min
  = 10 rad/s
51. Body A of mass 4m moving with speed u collides with another body B of mass 2m, at rest. The collision is head
on and elastic in nature. After the collision the fraction of energy lost by the colliding body A is :
(1) 
1
9
(2) 
8
9
(3) 
4
9
(4) 
5
9
Ans. (2)
Sol.
4m
A
u
2m
B
rest
4m
v
1 2m
v
2
-
= ==
+
1
4m 2m 2mu u
vu
4m 2m 6m 3
Fraction of energy lost = 
æö
-
ç÷
èø
2
2
2
1 1u
(4m)u (4m)
2 23
1
(4m)u
2
           = -=
18
1
99
52. The speed of a swimmer in still water is 20 m/s. The speed of river water is 10 m/s and is flowing due east.
If he is standing on the south bank and wishes to cross the river along the shortest path, the angle at which
he should make his strokes w.r.t. north is given by :
(1) 30° west (2) 0° (3) 60° west (4) 45° west
Ans. (1)
Sol. v = 20 m/s
u = 10 m/s
u
v
q
q= ==
u 101
sin
v 202
Þq = 30° west
3
53. A mass m is attached to a thin wire and whirled in a vertical circle. The wire is most likely to break when :
(1) the mass is at the highest point (2) the wire is horizontal
(3) the mass is at the lowest point (4) inclined at an angle of 60° from vertical
Ans. (3)
Sol. T ? mg cos q = 
2
mv
R
q
m
T
mg
T will be maximum when q = 0°,
When mass is at lowest point.
54. The displacement of a particle executing simple harmonic motion is given by
y = A
0
 + Asinwt + Bcoswt.
Then the amplitude of its oscillation is given by :
(1) 
++
22
0
A AB
(2) 
+
22
AB
(3) ++
22
0
A (A B) (4) A + B
Ans. (2)
Sol. y = A
0
 + A sin wt + B cos wt
y = A
0
 +
22
AB + sin (wt + f)
A
0
 is mean position, and 
22
AB + is amplitude
55. A 800 turn coil of effective area 0.05 m
2
 is kept perpendicular to a magnetic field 5 × 10
?5
 T. When the plane
of the coil is rotated by 90° around any of its coplanar axis in 0.1 s, the emf induced in the coil will be :
(1) 2 V (2) 0.2 V (3) 2 × 10
?3 
V (4) 0.02 V
Ans. (4)
Sol. Given
N = 800, A = 0.05 m
2
, B = 5 × 10
?5
 T
Dt = 0.15 s
As e = 
f-f-
=-
DD
fi
( ) (0 NBA)
?
tt
  = 
-
´ ´ ´´
?52
800 5 10 5 10
0.1
 = 0.02 V
56. Average velocity of a particle executing SHM in one complete vibration is :
(1) 
w A
2
(2) Aw (3) 
w
2
A
2
(4) Zero
Ans. (4)
Sol. Displacement = zero in one complete oscillation
Þ Average velocity = =
Displacement
0
T
4
 
57. A soap bubble, having radius of 1 mm, is blown from a detergent solution having a surface tension of
2.5 × 10
?2
 N/m. The pressure inside the bubble equals at a point Z
0 
below the free surface of water in a container .
Taking g = 10 m/s
2
 density of water = 10
3
 kg/m
3
, the value of Z
0
 is :-
(1) 100 cm (2) 10 cm (3) 1 cm (4) 0.5 cm
Ans. (3)
Sol. P = P
0
 + rgZ
0
.........(i)
Also,  P = P
0
 + 
4T
R
.........(ii)
From (i) & (ii)
rgZ
0
 =
4T
R
\ Z
0
 = 
2
33
4T 4 2.5 10
gR 10 10 10
-
-
´´
=
r ´´
= 10
?2
 m = 1 cm
58. A copper rod of 88 cm and an aluminum rod of unknown length have their increase in length independent of
increase in temperature. The length of aluminum rod is : (a
Cu
 = 1.7 × 10
?5
 K
?1
 and a
Al
 = 2.2 × 10
?5
 K
?1
)
(1) 6.8 cm (2) 113.9 cm (3) 88 cm (4) 68 cm
Ans. (4)
Sol. At any temperature
(D l)
Cu 
= (Dl)
Al
l
1
a
1
DT = l
2
a
2
DT
88 × 1.7 × 10
?5
 = l
2
 × 2.2 × 10
?5
l
2
 = 68 cm
59. The unit of thermal conductivity is :
(1) J m K
?1
(2) J m
?1
 K
?1
(3) W m K
?1
(4) W m
?1
 K
?1
Ans. (4)
Sol.
dQ dT
(K)A
dt dx
=-
2
J kelvin
(K)m
sm
=
(K) = watt m
?1
 K
?1
60. When a block of mass M is suspended by a long wire of length L, the length of the wire become (L+l). The
elastic potential energy stored in the extended wire is :-
(1) Mgl (2) MgL (3) 
1
2
 Mgl (4) 
1
2
 MgL
Ans. (3)
Sol. U = 
1
2
(force)(elongation)
==
11
(Mg) Mg
22
ll
5
61. A disc of radius 2m and mass 100 kg rolls on a horizontal floor. Its centre of mass has speed of
20 cm/s. How much work is needed to stop it ?
(1) 3J (2) 30 kJ (3) 2 J (4) 1 J
Ans. (1)
Sol. W
all
 = DKE
Þ
æö
=-+
ç÷
èø
2
2
cm 2
1K
W 0 mv1
2 R
Þ W = ?3J
62. In an experiment, the percentage of error occurred in the measurment of physical quantities A, B, C and D
are 1%, 2%, 3% and 4% respectively. Then the maximum percentage of error in the measurement X, where
=
2 1/2
1/33
AB
X
CD
, will be :
(1) 
æö
ç÷
èø
3
%
13
(2) 16% (3) ?10% (4) 10%
Ans. (2)
Sol. =
2 1/2
1/33
AB
x
CD
D D D DD
= + ++
x 2A 1B 1C D
3
x A 2B 3C D
   
D
Þ ´ = + ++
x 11
 1002(1%) (2%) (3%)3(4%)
x 23
= 16%
63. A body weighs 200 N on the surface of the earth. How much will it weigh half way down to the centre of the
earth ?
(1) 150 N (2) 200 N (3) 250 N (4) 100 N
Ans. (4)
Sol. g' = g
d
1
R
æö
-
ç÷
èø
g' = g
R /2
1
R
æö
-
ç÷
èø
mg' = mg
1
2
æö
ç÷
èø
W' = 200
1
2
æö
ç÷
èø
= 100 N
64. Which colour of the light has the longest wavelength ?
(1) red (2) blue (3) green (4) violet
Ans. (1)
Sol. Longest wavelength is of red colour.