When a system is in equilibrium , 2 conditions are met. 1) Principle of Moment (POM): Sum of anticlockwise moment = Sum of clockwise moment 2) Net force = 0N; all forces are balanced: Total downward forces = Total upward forces Whenever a force passed through the pivot point, that force will not create any moment as there is no perpendicular distance from the force to the pivot. Hence this force will not be included in the calculation of moments.

There are 3 scenarios with slight variations. Calculate the force F needed to pull the block up the inclined plane. View the video below to understand how to solve these types of question.

Though slinky coil is commonly used to demonstrate transverse and longitudinal waves, you must not quote it as an example for either of the waves. Transverse waves are waves in which the direction of the wave is perpendicular to the direction of the vibration of the particles. Examples are light wave, water wave or all the waves in the electromagnetic spectrum (which light is one of the waves. Longitudinal waves are waves in which the direction of the wave is parallel to the direction of the vibration of the particles.  Example is sound wave (inludes ultrasound and infrasound) Transverse Waves (slinky coil) Longitudinal Waves (slinky coil) Transverse Waves Animation Longitudinal Waves Animation

When an object is oscillating or vibrating in a wave motion , the speed of the object varies along the path. In this video, there are 3 examples of vibrating object. 1) Mass vibrating vertically from a spring 2) Pendulum bob oscillating 3) A particle vibrating up and down on a transverse wave In general, when the object is at the extreme ends of the oscillation or vibration , it is momentarily at rest . Hence its KE at these points is minimum or 0 J . And in the middle that is where the object is travelling the fastest , hence the KE is the maximum .