NCERT Solutions for Class 9 Science Chapter 8
Motion
NCERT Books for Session 2022-2023
CBSE Board and UP Board
Exercises Questions
Page No-113
Questions No-10
An artificial satellite is moving in a circular orbit of radius 42250 km. Calculate its speed if it takes 24 hours to revolve around the earth.
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Here,
r = 42250 km = 42250000 m
T = 24 h = 24 × 60 × 60 s
Using Speed, v = 2πr ÷ T
v = (2 × 3.14 × 42250000) ÷ (24 × 60 × 60) m/s
= 3070.9 m/s = 3.07 km/s
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To find the speed of the artificial satellite moving in a circular orbit around the Earth, we can use the formula relating the circumference of the orbit to the time taken for one revolution.
The formula for the circumference of a circle is 2 x π x radius
Given:
– Radius of the orbit r = 42250 km
– Time taken for one revolution T = 24 hours
Calculations:
The circumference of the circular orbit:
Circumference = 2 x π x radius = 2 x π x 42250 km
The speed of the satellite is given by the formula:
Speed = Circumference / Time taken for one revolution
First, let’s convert the time from hours to seconds because the speed is usually measured in distance per unit time in seconds.
Given: 1 hour = 3600 seconds
Time taken for one revolution in seconds = 24 hours 3600 seconds/hour = 86400 seconds
Now, calculate the speed:
Speed = (2 x π x 42250 km) / (86400 seconds)
Speed ≈ (2 x 3.1416 x 42250 km) / (86400 seconds)
Speed ≈ 265258 km) / (86400 seconds)
Speed ≈ 3.07 km/s
Therefore, the speed of the artificial satellite moving in a circular orbit of radius 42250 km, taking 24 hours to revolve around the Earth, is approximately 3.07 kilometers per second.