Rocket propulsion is a classic example of Newton's third law of motion. Fuel combustion leads to the ejection of gases at a high velocity, which provides the necessary force for flight as the rocket gets propelled in outer space. The principle of momentum conservation holds true for a system of rocket and fuel in space. The initial momentum of the rocket containing the fuel is equal to the final momentum, which is the sum of the rocket's momentum and the momentum of the expelled gases. If the direction of the rocket is along the positive x-axis, the expelled gases with mass dmex travel in the negative x-direction with a velocity vex. Here, the initial momentum of the rocket is mv. Due to fuel combustion for time dt, the momentum of expelled gases and the momentum for the rocket is calculated. Expressing the equation in terms of the magnitude, the equation is simplified further and neglecting the smaller terms from the equation, an equation for conservation of linear momentum for the rocket is obtained.