Types of Forces
friction is a contact force friction occurs when force is applied on one object by another the more the force the more friction. This conversation is already closed. The normal force is one component of the contact force between two objects, acting perpendicular to their interface. The frictional force is the. friction: A force that opposes two objects sliding against each other. .. The frictional force is independent of the relative velocity between the.
Now, it's time to include this very real force and see what happens. What are the forces of static and kinetic friction?
Parking your car on the steep hills of San Francisco is scary, and it would be impossible without the force of static friction. This is the same force that allows you to accelerate forward when you run.Kinetic Friction and Static Friction Physics Problems, Forces, Free Body Diagrams, Newton's Laws
Your planted foot can grip the ground and push backward, which causes the ground to push forward on your foot. We call this "grippy" type of friction, where the surfaces are prevented from slipping across each other, a static frictional force.
Types of Forces
If there were absolutely no friction between your feet and the ground, you would be unable to propel yourself forward by running, and would simply end up jogging in place similar to trying to run on very slippery ice. Now, if you park on a hill that is too steep, or if you are being pushed backward by a Sumo wrestler you're probably going to start sliding. Even though the two surfaces are sliding past each other, there can still be a frictional force between the surfaces, but this sliding friction we call a kinetic frictional force.
For example, a person sliding into second base during a baseball game is using the force of kinetic friction to slow down. If there were no kinetic friction, the baseball player would just continue sliding yes, this would make stealing bases in baseball difficult.
Explore the relationships between ideas about forces and friction in the Concept Development Maps - Laws of Motion Friction can slow things down and stop stationary things from moving.
In a frictionless world, more objects would be sliding about, clothes and shoes would be difficult to keep on and it would be very difficult for people or cars to get moving or change direction.
Students should be encouraged to consider how dependant their world is on the beneficial action of friction. Encourage students to consider both the positive and negative effects of friction on their everyday actions and experiences.
Ask students to identify what actions and tasks we do easily because of friction and what actions and tasks are made more difficult for example, consider walking, surfing and snow skiing.
| CK Foundation
The idea that surfaces have tiny bumps provides a useful model for explaining the cause and effect of friction. Students should discuss this model in an attempt to build an understanding of what the microscopic surfaces may look like and how they interact with each other Research: Students should be encouraged to explain why, in terms of the model of surface bumps pushing against each other, applying oil or lubricant to the contact surfaces can reduce the friction and allow them to move more freely.
Students should be encouraged to identify in which direction the friction force acts in a variety of simple situations and consider examples of everyday situations where friction is deliberately increased and reduced.
A good discussion example is the purpose of using hand grips and engine oil lubricants. They could explore the reasons for the wide variation in the design of shoes and in particular the soles of shoes created for specific purposes for example: Encourage students to examine the frictional advantages of each of the designs.
What is friction?
A book is at rest on a flat piece of wood that is inclined at a small angle to a table. Gradually the angle between the wood and the table is increased.
Two similar blocks of dry soap are pushed across a smooth table top. For one block of soap the table is dry and for the other block the table has been wet with a water detergent mix. Ask students to compare the size of the pushing force required to make the bars move.
A student slides down a plastic slippery slide covered with water and then repeats the experience with a soapy solution spread across the surface. After exploratory discussion, invite students to write about what a world would look like without friction.