Since we all know that the gravitational force on sun is 274m/s , so my question is that then why the earth gets closer and gets farer away from sun , is this is shown us to just explain anything related it or it actually is this if it is pls give me proper explanation.

Actually the Earth is drifting aeaw from the sun.

And it is not due to the gravitational force but due to the tidal acceleration.
The gravitational force simply tries to hold the Earth in its orbit.


The Earth is slowly drifting away from the sun.
Tidal acceleration is an effect of the tidal forces between an orbiting natural satellite and the primary object that it orbits . The acceleration causes a gradual recession of a satellite in a prograde orbit away from the primary, and a corresponding slowdown of the primary's rotation. The process eventually leads to tidal locking, usually of the smaller first, and later the larger body. The Earth–Moon system is the best studied case where this process is driving the moon’s orbit outward: Tides raised by the moon in our oceans are gradually transferring Earth’s rotational energy to lunar motion. As a consequence, each year the moon’s orbit expands by about 4 cm and Earth’s rotation slows by 0.000017 second.
Russian dynamicists Gregoriy A. Krasinsky and Victor A. Brumberg to calculated in 2004, that the sun and Earth are gradually moving apart. The sun and Earth are literally pushing each other away due to their tidal interaction.
Earth’s mass is raising a tiny but sustained tidal bulge in the sun. This causes the sun’s rotation rate to slow by 3 milliseconds per century (0.00003 second per year). The distance between the Earth and sun is growing 15 cm per year because the sun is losing its angular momentum. [1]
This and the expansion of space at 75 km per second per megaparsec will move Earth's orbit 40–50 million miles farther from the Sun by the time the Sun turns into a red giant.