Exam Questions - Newton's law of restitution
Exam Questions - Newton’s law of restitution
Section 1: Understanding Newton’s Law of Restitution
- Familiarise yourself with the principles of Newton’s Law of Restitution. This law illustrates the relationship between the speeds of two bodies before and after an impact.
- The central concept is the coefficient of restitution, a value that shows how much kinetic energy is conserved in a collision, represented by ‘e’.
Section 2: Applying Newton’s Law of Restitution
- The basic equation derived from Newton’s law of restitution is e = (v2’ - v1’) / (v1 - v2), where v1 and v2 are the initial velocities of the two bodies before the collision, and v1’ and v2’ are their velocities after the collision.
- Be aware that ‘e’ can’t be less than 0 nor more than 1. If ‘e’ equals 1, then the collision is perfectly elastic meaning no mechanical energy is lost. In contrast, if ‘e’ equals 0, the collision is perfectly inelastic; this means the bodies do not separate post-collision.
Section 3: Problem-Solving Strategies for Newton’s Law of Restitution
- To answer questions on Newton’s Law of Restitution, it’s important to understand how to apply the basic equation to different scenarios, such as head-on collisions or incidents involving angle changes.
- Pay close attention to the units of measurement throughout all your calculations, ensuring they are consistent. If not, make necessary conversions. For instance, if speed is given in km/hr, you may need to convert it to m/s, since the standard unit for velocity is metres per second.
- If a question involves an object bouncing off a wall or floor, remember that the speed of the wall or floor is zero relative to the bouncing object.
Section 4: Expanding Your Understanding
- Deepen your understanding by practising a variety of exercises involving the law of restitution, including solving for unknowns.
- Draw diagrams to help visualise scenarios and understand the direction of velocities, particularly in questions involving non-head-on collisions.
- Work through past problem sets and study solutions to understand the preferred method of responding to questions.