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<h2 class="wp-block-heading" id="h-introduction">Introduction</h2>
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<p>Good day, students!<br>Welcome to this detailed physics tutorial where we explore <strong>100-level university physics past questions</strong>, compiled from the <strong>University of Abuja</strong> and the <strong>Federal University of Technology, Akure (FUTA)</strong>.</p>
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<p>In this session, we will focus on the <strong>Law of Conservation of Linear Momentum</strong> and how it relates to <strong>rocket propulsion</strong> — a key topic in <strong>mechanics and motion</strong>. This topic is essential for undergraduate physics students and those preparing for engineering entrance exams.</p>
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<p>You can watch the full class in the video below:</p>
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https://www.youtube.com/watch?v=CdrXFpVyLEI&t=15s
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<h2 class="wp-block-heading" id="h-question-1-state-and-explain-the-law-of-conservation-of-linear-momentum">Question 1: State and Explain the Law of Conservation of Linear Momentum</h2>
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<p><strong>Question:</strong><br>State and explain the law of conservation of linear momentum. Use it to derive the principle of rocket propulsion.</p>
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<h3 class="wp-block-heading" id="h-definition-of-linear-momentum">Definition of Linear Momentum</h3>
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<p><strong>Linear momentum (p)</strong> is defined as the product of <strong>mass (m)</strong> and <strong>velocity (v)</strong> of an object: p=mvp = mvp=mv</p>
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<p>The <strong>Law of Conservation of Linear Momentum</strong> states that:</p>
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<p>In a closed system of particles (where no external force acts), the <strong>total momentum before an interaction</strong> is equal to the <strong>total momentum after the interaction</strong>.</p>
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<h3 class="wp-block-heading" id="h-real-life-application-rocket-and-jet-propulsion">Real-Life Application: Rocket and Jet Propulsion</h3>
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<p>Let’s relate this principle to <strong>rocket propulsion</strong>:</p>
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<li>When a rocket launches from Earth, it <strong>expels gas backward</strong> at high speed.</li>
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<li>According to Newton’s Third Law and momentum conservation, the rocket moves <strong>forward</strong> in the opposite direction.</li>
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<p>Imagine this:</p>
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<li>If the <strong>rocket</strong> is moving right,</li>
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<li>The <strong>exhaust gas</strong> is expelled left.</li>
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<p>The momentum of the gas and the rocket remain <strong>equal and opposite</strong>, ensuring the total system momentum stays constant.</p>
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<h3 class="wp-block-heading" id="h-mathematical-representation">Mathematical Representation:</h3>
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<p>Let:</p>
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<li>M be the <strong>mass of the rocket</strong> before expelling gas</li>
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<li>v be the <strong>velocity of the rocket</strong></li>
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<li>m be the <strong>mass of expelled gas</strong></li>
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<li>u be the <strong>velocity of the gas</strong></li>
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<figure class="wp-block-image size-full"><img src="https://allcbts.com/wp-content/uploads/2025/07/f7.gif" alt="" class="wp-image-26037"/></figure>
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<p><mark style="background-color:rgba(0, 0, 0, 0)" class="has-inline-color has-vivid-cyan-blue-color"><strong>Watch more educational videos and past questions:</strong> </mark><a href="https://youtube.com/@allcbts">https://youtube.com/@allcbts</a></p>
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<h2 class="wp-block-heading" id="h-key-insights">Key Insights</h2>
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<li>Rocket propulsion relies on the <strong>reaction</strong> from gas ejection.</li>
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<li>The system’s <strong>total momentum</strong> remains conserved at every point.</li>
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<li>This principle explains the <strong>backward thrust</strong> that accelerates rockets forward in space.</li>
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