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Byju's Answer
Standard XII
Physics
Work Energy Theorem
Because of th...
Question
Because of the friction between the water in oceans with the earth's surface, the rotational kinetic energy of the earth is continuously decreasing. If the earth's angular speed decreases by 0⋅0016 rad/day in 100 years, find the average torque of the friction on the earth. Radius of the earth is 6400 km and its mass is 6⋅0 × 10
24
kg.
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Solution
Rate of change of angular velocity, i.e., angular acceleration,
α =
0
.
0016
100
rad
/
day
⇒
α
=
0
.
0016
86400
2
×
100
×
365
1
year
=
365
days
=
365
×
86400
sec
Torque produced by the ocean water in decreasing the Earth's angular velocity,
τ
=
I
α
=
2
5
m
r
2
α
=
2
5
×
6
×
10
24
×
64
×
10
5
2
×
0
.
0016
86400
2
×
100
×
365
=
5
.
8
×
10
20
N
-
m
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