What is the approximate tangential speed of an object orbiting Earth with a radius of [tex]1.8 \times 10^8 \, \text{m}[/tex] and a period of [tex]2.2 \times 10^4 \, \text{s}[/tex]?

A. [tex]7.7 \times 10^{-4} \, \text{m/s}[/tex]
B. [tex]5.1 \times 10^4 \, \text{m/s}[/tex]
C. [tex]7.7 \times 10^4 \, \text{m/s}[/tex]
D. [tex]5.1 \times 10^5 \, \text{m/s}[/tex]



Answer :

To determine the tangential speed of an object orbiting Earth, we can use the formula for tangential speed:

[tex]\[ v = \frac{2 \pi r}{T} \][/tex]

where:
- [tex]\( v \)[/tex] is the tangential speed,
- [tex]\( r \)[/tex] is the radius of the orbit,
- [tex]\( T \)[/tex] is the period of the orbit.

Let's plug in the values provided in the problem:
- Radius ([tex]\(r\)[/tex]) = [tex]\( 1.8 \times 10^8 \)[/tex] meters,
- Period ([tex]\(T\)[/tex]) = [tex]\( 2.2 \times 10^4 \)[/tex] seconds.

Now, substituting these numbers into the formula:

[tex]\[ v = \frac{2 \pi \times 1.8 \times 10^8 \, \text{m}}{2.2 \times 10^4 \, \text{s}} \][/tex]

We need to calculate the numerator first:

[tex]\[ 2 \pi \times 1.8 \times 10^8 \][/tex]

Multiplying [tex]\(2 \pi \approx 6.2832\)[/tex] by [tex]\(1.8 \times 10^8\)[/tex]:

[tex]\[ 2 \pi \times 1.8 \times 10^8 \approx 6.2832 \times 1.8 \times 10^8 \][/tex]
[tex]\[ \approx 11.30976 \times 10^8 \][/tex]

Next, we divide this value by the period:

[tex]\[ v = \frac{11.30976 \times 10^8 \, \text{m}}{2.2 \times 10^4 \, \text{s}} \][/tex]

Performing the division:

[tex]\[ v \approx \frac{11.30976 \times 10^8}{2.2 \times 10^4} \][/tex]
[tex]\[ v \approx 5.140787878 \times 10^4 \, \text{m/s} \][/tex]

Rounding this value to two significant figures:

[tex]\[ v \approx 5.1 \times 10^4 \, \text{m/s} \][/tex]

So, the approximate tangential speed of the object is:

[tex]\[ \boxed{5.1 \times 10^4 \, \text{m/s}} \][/tex]