A particle is fired vertically upward with a speed of 15 km s-1. With what speed will it move in interstellar space. Assume only earth’s gravitational field.
Let the mass of the particle be m and the initial velocity
Here, initial kinetic energy,
Initial potential energy,
Let the final velocity be . Hence, final kinetic energy is
And since the particle is drifting in space, under no influence of gravity, its final potential energy
Now, using energy conservation,