NEET Physics: Law of conservation of linear momentum and its applications Practice Questions
12 free multiple-choice questions on Law of conservation of linear momentum and its applications (Laws of Motion) for NEET Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. A cannon of mass 10 kg fires a shell of mass 0.5 kg horizontally with a velocity of 200 m/s. What is the recoil velocity of the cannon?
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Correct answer: C — 250 m/s
By conservation of linear momentum, the total momentum of the system (cannon + shell) is conserved. Initial momentum = Final momentum. M u = (M+m) v. (10 kg) × (262.5 m/s) = (10 kg + 0.5 kg) × v. 2625 = 10.5 v. v = 2625 / 10.5 = 250 m/s.
Q2. The product of mass and velocity gives the linear momentum of an object. What is the SI unit for linear momentum?
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Correct answer: D — kg⋅m/s
Linear momentum (p) is calculated as mass (m) times velocity (v), so the unit is kilogram meter per second (kg⋅m/s).
Q3. If the total momentum of two colliding objects is conserved, it implies that the internal forces exerted between the objects must be balanced. This is a direct consequence of which principle?
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Correct answer: C — Newton's Third Law
Conservation of momentum arises because the internal forces between the interacting bodies are equal and opposite, ensuring that the total momentum of the system remains unchanged.
Q4. A body of mass M moving with velocity V collides with a stationary body of mass m. If the collision is perfectly elastic and no external forces act on the system, what is the total linear momentum of the system immediately after the collision?
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Correct answer: A — (M+m)V
In the absence of external forces, the total linear momentum of a system is conserved. If the collision is perfectly elastic, the total momentum is the sum of the individual momenta before the collision. If the bodies stick together and move with a common final velocity V, the total momentum is (M+m)V (assuming the initial velocity of the first body was V and the second was 0).
Q5. A system is considered closed if:
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Correct answer: D — No net external forces act on it
A system is closed in the context of momentum conservation if there are no net external forces acting upon it, ensuring momentum remains constant.
Q6. In an isolated system, the total linear momentum is conserved. This principle is directly related to which of Newton's laws?
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Correct answer: A — Newton's First Law (Law of Inertia)
The conservation of momentum is a direct consequence of Newton's First Law of Motion, which defines the state of rest or uniform motion when no net external force is present.
Q7. If the momentum of object A is 10 kg m/s and the momentum of object B is 5 kg m/s, and they interact internally without any external forces, what is the total momentum of the combined system?
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Correct answer: D — 15 kg m/s
According to the law of conservation of momentum, the total momentum is the sum of the individual momenta: 10 kg m/s + 5 kg m/s = 15 kg m/s.
Q8. In the absence of external forces, the total linear momentum of a system of objects remains constant. This principle is based on which fundamental law of motion?
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Correct answer: A — Law of Conservation of Linear Momentum
The Law of Conservation of Linear Momentum states that if no net external force acts on a system, the total linear momentum of that system remains constant.
Q9. When a system of particles undergoes an internal collision, the total linear momentum of the system:
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Correct answer: D — Remains constant
The law of conservation of linear momentum states that the total momentum of a system remains constant, even during internal interactions, provided no external forces act on the system.
Q10. Two objects of masses m₁ and m₂ are moving in the same direction with velocities v₁ and v₂ respectively. If the total momentum of the system is conserved, which of the following statements must be true?
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Correct answer: D — The total momentum remains constant, regardless of the internal forces acting between them.
The law of conservation of linear momentum states that the total momentum of a system remains constant if no net external force acts on the system. This principle applies even when internal forces are present between the objects, as these forces are internal and their internal momentum contributions cancel out.
Q11. A spaceship travels from Point A to Point B. If the spaceship slows down, its momentum will:
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Correct answer: A — Decrease
Momentum is the product of mass and velocity. If the spaceship slows down (velocity decreases) while its mass remains constant, its linear momentum must decrease.
Q12. For the linear momentum of a system to be conserved, the net external force acting on the system must be:
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Correct answer: B — Zero
Momentum is conserved only if the net external force acting on the system is zero (i.e., the system is isolated or in equilibrium).
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