Physics
Physics
1st Edition
Walker
ISBN: 9780133256925
Textbook solutions

All Solutions

Page 315: Practice Problems

Exercise 16
Step 1
1 of 3
$textbf{Given: }$

The mass of Earth is $m_{E} = 5.97 times 10^{24} mathrm{~kg}$.The radius of Earth is $R_{E} = 6.37 times 10^{6} mathrm{~m}$. The height of the space station is $h = 370 mathrm{~km}$.

$textbf{Required: }$

Finding the acceleration due to the gravity at the altitude of the International Space Station’s orbit.

Step 2
2 of 3
$textbf{Calculation: }$

According to Newton’s second law, the force due to the gravity (Weight) is given by

$$
begin{align*}
F &= W \
&= m_{1} ~ a \
end{align*}
$$

As Newton’s law of universal gravitation, The force of gravity between two objects is given by

$$
begin{align*}
F &= G ~ dfrac{ m_{1} ~ m_{E} }{ r^{2} } \
&= m_{1} ~ a \
&= G ~ dfrac{ m_{1} ~ m_{E} }{ left( R_{E} + h right)^{2} } \
end{align*}
$$

Rearrange and solve for the acceleration due to the gravity at the altitude of the International Space Station’s orbit:

$$
begin{align*}
a &= G ~ dfrac{ m_{E} }{ left( R_{E} + h right)^{2} } \
&= 6.67 times 10^{-11} mathrm{~N cdot m^{2}/kg^{2}} ~ dfrac{ 5.97 times 10^{24} mathrm{~kg} }{ left( 6.37 times 10^{6} mathrm{~m} + 3.7 times 10^{5} mathrm{~m} right)^{2} } \
&= 8.766 mathrm{~m/s^{2}}
end{align*}
$$

So, the acceleration due to the gravity at the altitude of the International Space Station’s orbit is $8.766 mathrm{~m/s^{2}}$.

Result
3 of 3
The acceleration due to the gravity at the altitude of the International Space Station’s orbit is $8.766 mathrm{~m/s^{2}}$.
Exercise 17
Step 1
1 of 4
$textbf{Given: }$

The mass of Earth is $m_{E} = 5.97 times 10^{24} mathrm{~kg}$.The radius of Earth is $R_{E} = 6.37 times 10^{6} mathrm{~m}$. The acceleration due to gravity is $a = dfrac{g}{2}$.

$textbf{Required: }$

Finding the altitude above Earth’s surface (height).

Step 2
2 of 4
$textbf{Calculation: }$

According to Newton’s second law, the force due to the gravity (Weight) is given by

$$
begin{align*}
F &= W \
&= m_{1} ~ a \
end{align*}
$$

As Newton’s law of universal gravitation, The force of gravity between two objects is given by

$$
begin{align*}
F &= G ~ dfrac{ m_{1} ~ m_{E} }{ r^{2} } \
&= m_{1} ~ a \
&= G ~ dfrac{ m_{1} ~ m_{E} }{ left( R_{E} + h right)^{2} } \
end{align*}
$$

Rearrange and solve for the acceleration due to the gravity at the altitude of the International Space Station’s orbit:

$$
begin{align*}
a &= G ~ dfrac{ m_{E} }{ left( R_{E} + h right)^{2} } \
&= dfrac{g}{2} \
end{align*}
$$

Step 3
3 of 4
$textbf{Calculation: }$

Rearrange and solve for the altitude above Earth’s surface (height):

$$
begin{align*}
left( R_{E} + h right)^{2} &= dfrac{ 2 ~ G ~ m_{E} }{g} \
h &= sqrt{ dfrac{ 2 ~ G ~ m_{E} }{g}} – R_{E} \
&= sqrt{ dfrac{ 2 times 6.67 times 10^{-11} mathrm{~N cdot m^{2}/kg^{2}} times 5.97 times 10^{24} mathrm{~kg} }{9.8 mathrm{~m/s^{2}} }} – 6.37 times 10^{6} mathrm{~m} \
&= 2.645 times 10^{6} mathrm{~m}
end{align*}
$$

So, the altitude above Earth’s surface (height) is $2.645 times 10^{6} mathrm{~m}$.

Result
4 of 4
The altitude above Earth’s surface (height) is $2.645 times 10^{6} mathrm{~m}$.
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