Question

A certain satellite orbiting Earth has a speed of about 17,000 miles/hour. What is its approximate speed expressed to the correct number of significant figures in kilometers/second? One kilometer is about 0.62 mile, and there are 3,600 seconds in an hour.
A.
2.9 km/s
B.
7.6 km/s
C.
38,000,000 km/s
D.
99,000,000 km/s

Answer 1

Answer:

B. 7.6 km/s

Explanation:

Given:

Speed of the satellite orbiting Earth is, $v=17000\ miles/hour$

In order to convert the speed from miles/hour to km/s, we need to convert miles to km and hour to seconds.

The conversion factors are:

0.62 miles = 1 km

∴ 1 mile = $\frac{1}{0.62}\ km$

1 hour = 3600 s

Now, 17000 miles/hour can be rewritten as:

$17000\times \frac{1\ mile}{1\ hour}\\\\=17000\times \frac{\frac{1}{0.62}\ km }{3600\ s}\\\\=\frac{17000}{0.62\times 3600}\ km/s\\\\=7.6\ km/s$

Therefore, the speed in km/s is 7.6 km/s.