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, you need to understand that friction is equal to the force required to move an object at a constant speed. In this case, the force required is 30 N.
First, we need to recognize that the force required to move the wagon at a constant speed is equal to the force of friction acting against it. So, the total force of friction is 30 N.
b) On a bicycle, reducing friction is desirable because it allows for smoother and more efficient movement. Friction can occur in various parts of a bicycle, such as the wheels, bearings, and chain.
To reduce friction on a bicycle, you would want to focus on areas where mechanical parts come into contact with each other. These areas include the wheel bearings, hub, headset, bottom bracket, and chain. Keeping these parts clean and properly lubricated is key to reducing friction.
To reduce friction in these areas, you can follow these steps:
1. Clean the parts thoroughly using a degreaser to remove any dirt, grime, or old lubricant.
2. Apply a suitable lubricant specifically designed for bicycles. Ensure that you apply lubricant sparingly, avoiding excess that can attract more dirt.
3. Regularly inspect and clean these parts, especially after riding in wet or dusty conditions.
c) The coefficient of kinetic friction is a value that represents the relationship between the force of friction acting on an object and the normal force pressing the object against the surface. It measures the amount of resistance between two surfaces when one is in motion relative to the other.
The coefficient of kinetic friction is denoted by the symbol μk. It is a dimensionless value that varies depending on the nature of the surfaces in contact. The equation to calculate kinetic friction force is:
Force of kinetic friction (Fk) = μk * normal force
Where:
- Fk is the force of kinetic friction
- μk is the coefficient of kinetic friction
- Normal force is the force exerted by a surface perpendicular to the object
By knowing the coefficient of kinetic friction, you can determine the magnitude of the force of friction on an object in motion.