Contact & Non-contact Forces

What are contact forces?

• The forces that require direct physical touch, or contact, between two objects.

• The forces that act at a distance without physical contact.

• The forces that are always attractive and never repulsive.

• The forces that are only present in solid objects.

What is the difference between static and kinetic friction?

• Static friction occurs when objects are in motion relative to each other.

• Kinetic friction is when objects are not moving relative to each other.

• Static friction is when objects touching are not moving relative to each other, while kinetic friction is when they slide past each other.

• There is no difference between static and kinetic friction.

Magnetic force

• A non-contact force which occurs between moving charges

• A contact force that acts between stationary objects

• A force that only occurs in magnetic materials

• A force that is always attractive between two objects

Electrical forces

• Non-contact forces which occurs between static (non-moving) charges

• Forces that act only on moving charges

• Contact forces that require physical touch

• Forces that can only be observed in magnetic fields

Gravitational force

• A non-contact force that pulls all objects with mass towards each other.

• A contact force that pushes objects apart.

• A force that only acts on objects in motion.

• A force that only affects objects with a temperature above absolute zero.

Normal Force

• A force that pulls objects towards the center of the Earth.

• A contact force that pushes up against an object when it is resting on a surface. It is perpendicular to the surface.

• A force that opposes the motion of an object in contact with a surface.

• A force that acts parallel to the surface of an object.

What are the two categories of forces?

• Friction and Gravity

• Contact and Non-contact forces

• Magnetic and Electric forces

• Tension and Compression

Static friction

• Type of friction in which objects are not moving relative to each other, but they are touching

• Type of friction that occurs when two surfaces slide past each other

• Type of friction that acts on an object at rest when a force is applied

• Type of friction that occurs in fluids when objects move through them

What is a force?

• A type of energy that can be converted into work.

• A push or pull that can make an object change speed, direction, or shape.

• A measure of the mass of an object.

• A reaction that occurs when two objects collide.

Kinetic friction

• Type of friction in which objects are moving relative to each other with their surfaces touching

• Type of friction that occurs when objects are at rest relative to each other

• Type of friction that opposes the motion of an object in a fluid

• Type of friction that occurs between two surfaces in contact without movement