Escape velocity of a body of \(1 \mathrm{~kg}\) on a planet is $100 \mathrm{~ms}^{-1}$. Gravitational potential energy of the body at the planet is \(=\) $\begin{array}{ll}\text { (A) } \overline{-5000} & \text { (B) }-1000\end{array}$ (C) \(-2400\) (D) 5000

Short Answer

Expert verified
The gravitational potential energy of the body at the planet's surface is \(-5000\mathrm{~J}\). So, the correct answer is (A) \(-5000\).

Step by step solution

01

Formula for escape velocity

To find the gravitational potential energy, we will first look at the formula for escape velocity. The escape velocity is given by: \(v_e = \sqrt{\frac{2GM}{r}}\) where \(v_e\) is the escape velocity, \(G\) is the gravitational constant, \(M\) is the mass of the planet, and \(r\) is the distance from the center of the planet to the body. Using the given escape velocity, \(100\mathrm{~ms^{-1}}\), we can calculate the value of \(\frac{2GM}{r}\).
02

Kinetic energy and gravitational potential energy

Next, we can relate kinetic energy (KE) and gravitational potential energy (GPE) to escape velocity. For a body to escape a planet's gravitational field, its kinetic energy needs to be equal to the gravitational potential energy: \(KE = GPE\) The kinetic energy of the body is given by: \(KE = \frac{1}{2}mv^2\) Using the escape velocity, the kinetic energy of the body is: \(KE = \frac{1}{2}(1\textrm{ kg})(100\textrm{ ms}^{-1})^2\) Now, the gravitational potential energy is: \(GPE = -\frac{GMm}{r}\) Since \(KE = GPE\), we have: \(\frac{1}{2}mv^2 = -\frac{GMm}{r} \Rightarrow \frac{1}{2}v^2 = -\frac{GM}{r}\)
03

Calculate the gravitational potential energy

Now we can solve for \(GPE\): \(-\frac{GM}{r} = \frac{1}{2}(100\textrm{ ms}^{-1})^2\) Let's plug in the value of \(\frac{2GM}{r}\) we got in step 1: \(GPE = -\frac{1}{2}(100\textrm{ ms}^{-1})^2 = -5000\mathrm{~J}\) The gravitational potential energy of the body at the planet's surface is -5000 J. So, the correct answer is (A) \(-5000\).

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