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QJEEM24Ph8607: JEE Main 2024 Physics - Class 11 JEEM24Ph8607 Solution: To project a body of mass m from earth's surface to infinity,…

To project a body of mass m from earth's surface to infinity, the required kinetic energy is (assume, the radius of earth is RE,g= acceleration due to gravity on the surface of earth):

Multiple Choice Options

  • A 1/2mgRE
  • B 4mgRE
  • C mgRE
  • D 2mgRE

Step-by-Step Verified Solution

The kinetic energy required to project a body of mass mm from the Earth's surface to infinity, also known as the escape kinetic energy, can be calculated using the concept of gravitational potential energy. The escape velocity vev_e is the velocity a body must have to escape the gravitational field of the Earth without any further propulsion. The formula for escape velocity is:

ve=2gREv_e = \sqrt{2gR_E}

Where gg is the acceleration due to gravity on the surface of Earth and RER_E is the radius of the Earth. The kinetic energy KK required for this is given by:

K=12mve2K = \frac{1}{2}mv_e^2

Substituting the escape velocity formula into the kinetic energy formula gives:

K=12m(2gRE)K = \frac{1}{2}m\left(2gR_E\right)

K=12×2×mgREK = \frac{1}{2} \times 2 \times mgR_E

K=mgREK = mgR_E

Therefore, the required kinetic energy to project a body of mass mm from Earth's surface to infinity is mgREmgR_E . So, the correct answer is:

Option C: mgREmgR_E

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