Explain frictional force
2.Explain why the efficiency of a machine is always less than 100%
1. Frictional force is a force that resists the relative motion or tendency of motion between two surfaces in contact with each other. It occurs due to the irregularities in the surfaces that come in contact with each other, causing resistance to their movement. Frictional force can be helpful in some situations, such as providing traction for vehicles or gripping surfaces for walking, but it can also be a hindrance, causing wear and tear on surfaces and reducing efficiency in machines.
2. The efficiency of a machine is always less than 100% because some of the energy input into the machine is lost as waste heat, sound, or other forms of energy that do not contribute to the desired output of the machine. This loss of energy is typically due to factors such as friction, air resistance, or vibrations within the machine itself. No machine can be 100% efficient because some energy will always be lost in the form of heat or other non-useful forms of energy during the conversion process. This is known as the principle of conservation of energy, which states that energy cannot be created or destroyed, only transformed from one form to another.