A planet with a mass of \(7.00 \cdot 10^{21} \mathrm{~kg}\) is in a circular orbit around a star with a mass of \(2.00 \cdot 10^{30} \mathrm{~kg} .\) The planet has an orbital radius of \(3.00 \cdot 10^{10} \mathrm{~m}\). a) What is the linear orbital velocity of the planet? b) What is the period of the planet's orbit? c) What is the total mechanical energy of the planet?

Short Answer

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Question: A planet with mass m_p orbits around a star with mass m_s. The distance between the planet and the star is r. Find the linear orbital velocity (v), the period of the planet's orbit (T), and the total mechanical energy (E) of the planet. Answer: To find the linear orbital velocity (v), the period of the planet's orbit (T), and the total mechanical energy (E) of the planet, follow these steps: 1. Find the gravitational force between the planet and the star using Newton's law of universal gravitation: \(F = G\frac{m_pm_s}{r^2}\) 2. Determine the centripetal force keeping the planet in a circular orbit: \(F_c = m_pv^2/r\) 3. Set the equations from steps 1 and 2 equal to each other and solve for v: \(v=\sqrt{\frac{Gm_s}{r}}\) 4. Calculate the period of the planet's orbit (T): \(T=\frac{2\pi r}{v}\) 5. Calculate the total mechanical energy of the planet (E): \(E=KE + PE = \frac{1}{2}m_pv^2 - G\frac{m_pm_s}{r}\) Using the given values for m_p, m_s, and r, along with the gravitational constant G, calculate the linear orbital velocity, the period of the planet's orbit, and the total mechanical energy of the planet.

Step by step solution

01

Gravitational force

First, we want to find the gravitational force between the planet and the star. This can be done using Newton's law of universal gravitation: \(F = G\frac{m_pm_s}{r^2}\) Where \(F\) is the gravitational force, \(G\) is the gravitational constant (\(6.67 \cdot 10^{-11} \mathrm{N(m/kg)^2}\)), \(m_p\) is the mass of the planet, \(m_s\) is the mass of the star, and \(r\) is the distance between them.
02

Centripetal force

The centripetal force keeping the planet in a circular orbit is equal in magnitude to the gravitational force. The centripetal force can be expressed as: \(F_c = m_pv^2/r\) Where \(F_c\) is the centripetal force, \(m_p\) is the mass of the planet, \(v\) is the linear velocity, and \(r\) is the orbital radius.
03

Solve for linear orbital velocity

Since the gravitational force and centripetal force are equal, we can set the equations from steps 1 and 2 equal to each other and solve for \(v\): \(G\frac{m_pm_s}{r^2}=m_pv^2/r \Rightarrow v=\sqrt{\frac{Gm_s}{r}}\) Now, plug in the given values for \(G\), \(m_s\), and \(r\) to find the linear orbital velocity, \(v\).
04

Calculate the period of the planet's orbit

To find the period of the planet's orbit, we need to find the time it takes for the planet to travel around the circumference of its orbit, \(2\pi r\). We can find the period, \(T\), by dividing this distance by the linear orbital velocity, \(v\): \(T=\frac{2\pi r}{v}\) Using the linear orbital velocity found in step 3, calculate the period of the planet's orbit.
05

Calculate total mechanical energy

The total mechanical energy of the planet is the sum of its kinetic energy and gravitational potential energy. The kinetic energy, \(KE\), can be calculated as: \(KE=\frac{1}{2}m_pv^2\) The gravitational potential energy, \(PE\), can be calculated as: \(PE=-G\frac{m_pm_s}{r}\) The total mechanical energy, \(E\), is the sum of the kinetic energy and potential energy: \(E=KE + PE\) Calculate the kinetic energy and potential energy using the values found in step 3 and the given masses. Then, add the kinetic and potential energies together to find the total mechanical energy.

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