Forces, crit A study help

Contact forces

Physical contact between the applier of the force (called the agent) and the receiver of the force (called the receiver).

Requires different strengths, eg. The force needed to change a rigid & large shape is strong

Force

A force is a “push” or “pull” that acts on an object.

Any movement or stop “of” movement causing an object to move, exhilarate, change shape or cause motion.

Friction

Friction is a force that acts to oppose motion between any surfaces that are touching. Friction always acts parallel to the surface.

Mass vs weight

Weight is another name for the force of gravity acting on an object, specifically, this is the force of gravity acting on an object due to the moon/planet they are standing upon. Mass is a fundamental property of the object, a measure of how difficult it is to change the motion of that object, it’s constant, no matter where it goes in the universe.

How to calculate weight

Weight= Mass x Gravitational field strength

Mass units and equipment

Measured in Kilograms using a balance

Weight units and equipment

Measured in Newtons using a scale

Field forces

Non-contact forces

Example= gravitational, magnetism, electricity

Electromagnetic force

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Makes charged particles attract and repel one another and holds atoms together but it is also the force that is acting whenever atoms push against other atoms

Affects atoms by pulling negative electrons to positive protons.

Examples= Static, Upthrust, Normal, Friction

Medium strengths and range

Gravitational force

This force holds planets together, works over great distances and is the weakest of the three main forces.

Infinite range and weakest- impact on our daily lives

Strong nuclear force

This is the force that holds the nucleus together, and it is the strongest force in the universe. Although it is strong, this force only acts over a very short range. (The size of the nucleus.) 

* Very strong, small range

Gravity

A long range attractive force between all objects with mass.

Wavelength

Distance between peaks

Long=low

Short=high

Frequency

Waves/lines

What are the effects of shapes?

Change in shape, size, speed, direction in motion.

Example of effect of force acting on an object

A car exhilarating is a change in speed, a change in direction would be a tennis ball bouncing of a racket.

What is a free body diagram?

A free-body diagram shows all the forces acting on a single object in a diagram. 

The size of the arrows shows the magnitude(amount) of the force, and forces represented by arrows.

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What is normal force?

The word "normal" in **normal force** is not referring to ordinary or commonplace. The "normal" here refers to **perpendicular.**

Normal force= not when in air

Equation of work

Work(NM= JOULES=J)= force(N) \* distance(m)

(no factor can be zero, otherwise no work)

What is work?

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* **Work is whenever a force makes something move we can call this work**
* **In everyday life= anything requiring effort**

In physical sciences, work is defined as the force exerted on an object multiplied by the distance the object moves due to that force

Identification of Work been done:

You can tell if work has occurred if something isn’t in its first site/place

When do you say that no work has been done?

You can only use the force that is in the same direction/causing the direction of movement of the object in the equation for the “work” being done. Force has to act parallel to movement/motion of the object to calculate the work.

Has to be in the right direction!

The greater the ---, and/or the greater the---an object moves the more ---is done.

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(equation explanation)

force, distance, more work

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**Potential Energy**

Energy stored in a system due to how objects are arranged

Kinetic energy

energy due to motion

Gravitational Potential Energy

A ball held in the air can do work because when it is dropped it will be pulled by gravity. The ball has gravitational *potential energy*

Chemical Potential Energy

Fuels can do work because when they are burned, new bonds will be formed and energy will be released. Fuels have chemical potential energy. 

Heat(thermal) energy

Thermal energy refers to the energy contained within a system that is responsible for its temperature. Heat is the flow of thermal energy.

Light energy

Light energy is a kind of kinetic energy with the ability to make types of light visible to human eyes. Light is defined as a form of electromagnetic radiation emitted by hot objects like lasers, bulbs, and the sun. Light contains photons which are minute packets of energy.

Sound energy

Sound energy comes from vibrations moving through something

What energy is used in photosynthesis?

*The light energy from the Sun is converted to chemical energy by plants.*

Define pressure and state/ use the SI units for pressure

Pressure is the result of a **force being applied** over an area, defined as “force-per-unit-area”.  

Pressure= (N/m2)= force (Newtons)/Area(meters2)

Pascals( 1 Pa= 1 N/m2) are the SI units of pressure

Describe and explain the factors that affect the force of friction acting upon an object.

The factors that can affect the amount of friction acting on an object on a solid surface are the mass of the object, the type of surface it is on, and whether the object is moving or still. Angle?

State the law of conservation of energy