a) What is the total force of friction on a wagon’s wheels if it takes 30 N to move it at a constant speed across a bumpy path?

b) Where on a bicycle do you want to reduce friction? How is this done?

c What is meant by the coefficient of kinetic friction?

a) To find the total force of friction on the wagon's wheels, we can use the concept of Newton's first law of motion, which states that an object at a constant speed will experience a net force of zero. In this case, the force required to move the wagon at a constant speed is equal to the force of friction acting in the opposite direction. Hence, the total force of friction on the wagon's wheels is 30 N.

b) On a bicycle, reducing friction can significantly improve its performance. The areas where you would want to reduce friction are typically the contact points between moving components, such as the wheel bearings and the chain. To achieve this, you can follow these steps:

1. Lubrication: Apply lubricating oil or grease to the moving parts like the wheel bearings and the chain to reduce friction between them. This helps to decrease wear and tear and allows for smooth movement.

2. Regular Maintenance: It is essential to ensure that all the bicycle parts are clean, properly aligned, and well-maintained. By doing so, you can minimize friction-related issues and maximize the bike's efficiency.

3. Quality Components: Investing in high-quality, low-friction components can significantly reduce friction. This includes using high-quality ball bearings, well-designed chain lubricants, and low-resistance tires.

c) The coefficient of kinetic friction is an important term used to describe the level of friction between two surfaces when they are in relative motion. It is denoted as µ in equations. The coefficient of kinetic friction depends on the nature of the two surfaces in contact and is specific to a particular material combination.

Mathematically, the coefficient of kinetic friction (µk) is calculated as the ratio of the force of kinetic friction (Fk) to the normal force (Fn) acting between the two surfaces:

µk = Fk / Fn

The coefficient of kinetic friction determines how much resistance or frictional force exists between two objects when they are sliding or moving relative to each other. A higher coefficient of kinetic friction implies a greater resistance to motion, while a lower coefficient indicates a smoother and less resistive interaction between the surfaces.