Friction is really important when it comes to understanding how mechanical energy works.

Mechanical energy is how we measure the energy in a closed system. It includes two types of energy: potential energy (PE) and kinetic energy (KE). You can think of it like this:

Mechanical Energy (ME) = Potential Energy (PE) + Kinetic Energy (KE)

In a perfect closed system with no friction, the mechanical energy stays the same. But in the real world, we often have friction, which changes things. Friction is a type of force that takes energy away from how it was being used, and we call it a non-conservative force.

How Friction Affects Energy

1. Changes Energy:

   • Friction turns mechanical energy into heat or thermal energy. This heats up the surroundings and makes less mechanical energy available for doing work.

2. Work Against Friction:

   • We can measure the work done against friction with this formula:

   Work (W) = Frictional Force (F) × Distance (d) × cos(θ)

   Here, F is the force of friction, d is how far something moves, and θ is the angle between the direction of the force and the motion (which is 180° when friction acts against the motion, meaning cos(180°) = -1).

3. Bowling Example:

   • Let’s look at a bowling ball to see how this works. The kinetic energy of a rolling bowling ball can be calculated using the formula:

   Kinetic Energy (KE) = ½ × mass (m) × velocity squared (v²)

   For example, if we have a 3 kg bowling ball rolling at 5 m/s, we find the KE like this:

   KE = ½ × (3 kg) × (5 m/s)² = 37.5 Joules (J)

   Now, if friction does 10 J of work, the leftover mechanical energy will be:

   27.5 J (37.5 J - 10 J = 27.5 J)

In summary, friction has a big effect on the conservation of mechanical energy. It changes usable energy into heat, which means there’s less energy left for movement and work in any system.