Exam Questions - Momentum
Exam Questions - Momentum
Section 1: Understanding Momentum
- Grasp that momentum is a vector quantity that is the product of mass and velocity, given by p = m v.
- We calculate the momentum of an object moving in a straight line as the product of its mass and its velocity.
- The direction of the momentum vector is the same as the velocity vector.
Section 2: Conservation of Momentum
- Understand the Principle of Conservation of Momentum which states that in a closed system, total momentum before an event (like a collision or explosion) is equal to total momentum after the event.
- This is written mathematically as Total P_initial = Total P_final, where P is momentum.
- Realise that momentum is conserved only in the direction of motion.
Section 3: Impulse and Change in Momentum
- Learn that Impulse (also known as change in momentum) is given by the equation Impulse = Change in momentum = Final momentum - Initial momentum.
- Remember that an Impulse occurs whenever an object’s velocity changes (due to a force acting on it) which as a result changes the object’s momentum.
- Know that Impulse can also be calculated as the product of force and the time over which the force is applied. This is represented as Impulse = F t.
Section 4: Problem-Solving Techniques on Momentum
- Master the skill of drawing velocity-time and force-time graphs to understand momentum problems better.
- Always consider the directions when calculating momentums since it is a vector quantity. Assign positive and negative values accordingly.
- Use conservation principles (conservation of momentum) to solve problems involving collisions and explosions.
- Implement equations of motion and Newton’s Second Law where necessary to find unknowns.
- Practise a variety of momentum-related problems to get more familiar with various types of contexts and become proficient in using the concepts.
Section 5: Topics Related to Momentum
- Have an understanding of elastic and inelastic collisions. In an elastic collision both momentum and kinetic energy are conserved. In an inelastic collision, only momentum is conserved, not kinetic energy.
- Recognise the principle of recoil which is based on the conservation of momentum. For instance, when a gun is fired, the bullet gains forward momentum and the gun gains an equal amount of backward momentum. This is known as the ‘recoil’ of the gun.