physics term 1

atomic model description

atomic model description

An atom has a small, positively-charged nucleus surrounded by orbiting negatively-charged electrons.

density

mass kg / volume m³

upthrust

The force that keeps the object afloat

The Law of Displacement

The idea that an object completely submerged in a fluid (like water) will replace an amount of fluid equal to its own volume.

gases

.the least dense state of matter.

.The particles are free to move with negligible (tiny) forces between particles.

liquids

.This state is less dense than solids but more dense than gases.

.The particles in liquids can move around each other.

solids

.They are the most dense state of matter.

.The particles are packed tightly together.

calculating density of irregular shaped solids

• we can use the Law of Displacement to estimate its volume and a scale the find the mass.

• This is done using a displacement can, or a graduated measuring cylinder.

• The volume of displaced water is measured, and this is the volume of the object.

Displacement/ Eureka can

A can used to determine the volume of a solid.

calculating density of a liquid

• place a measuring cylinder on a scale and set the reading to zero.

• Pour the liquid into the cylinder and write down its mass and volume. Then calculate the density.

liquids and solids

States of matter that cannot be compressed since their particles are already touching

gas and liquid

states of matter in which the particles are arranged in a disordered pattern.

gas

a state of matter that fills its container because it has no fixed volume and its particles constantly move and spreads out.

liquid

a state of matter that takes the shape of its container

solid

a state of matter that has a fixed shape and arranged in an ordered pattern. It has a fixed shape because

conservation of mass

When a substance changes state, its mass is conserved (stays the same).

change of state is a physical process

when a substance changes state, it is reversible meaning it isn’t a chemical change

melting point

fusion point

kinetic theory of matter

The idea that all 3 states of matter are made of particles that are constantly moving

latent heat

the energy that is transferred to a substance without the substance's temperature changing. This happens when a substance is changing state.

specific latent heat

the latent heat per 1kg of mass. It is a way to standardise across objects that have different masses

what happens to latent heat

When a substance changes state, the temperature stops increasing because this energy is used to create or weaken bonds, rather than transfer kinetic energy to a substance’s particles.

heat

The amount of kinetic something has. It is measure in joules (J)

temperature

the measure of the average internal energy of all the particles in a substance. It is measured in degrees Celsius (⁰C) or kelvin (K)

temperature

The measure of how hot or cold something is

latent heat of fusion

When a solid becomes a liquid or a liquid becomes a solid, this hidden energy is called xxx

latent heat of vaporisation

When a gas becomes a liquid, or a liquid becomes a gas, this hidden energy is called xxx

calculating energy change for change of state

energy (j) =mass (kg) × latent heat (j/kg)

detecting latent heat

using a joulemeter and measuring energy supplied to change state

potential energy

energy stored in an object

internal energy

the total amount of energy in chemical and kinetic stores

specific latent heat of fusion experiment

• To determine water’s specific latent heat of fusion we use the equation: \n specific latent heat = energy change ÷ mass.

• Gently heat ice in a funnel until it melts. Then measure the mass of the melted ice (water in the beaker).

• Measure the amount of energy supplied by the heater using a joulemeter (this gives us the energy change).

• Calculate the specific latent heat of fusion using our equation above.

specific latent heat of vaporisation experiment

• To determine water’s specific latent heat of vapourisation we use the equation: \n specific latent heat = energy change ÷ change in mass.

• Measure the mass of water in a beaker.

• Boil some water and then measure the mass of the water again.

• Mass at the start - mass at the end = change in mass.

• Measure the amount of energy supplied by the heater using a joulemeter (this gives us the energy change).

• Calculate the latent heat of vapourisation using our equation above.

joulemeter

a device that measures the energy supplied

Thermal heat capacity experiment

The specific heat capacity of a substance is the amount of energy needed to increase the temperature of 1 kg of that substance by 1 °C.

• The heater increases the internal energy of the body and we measure this using a joulemeter.

• Measure the temperature of the body (object) at the start and measure the maximum temperature of the body at the end.

• Specific heat capacity = change in internal energy / (mass (kg) x maximum temperature rise (°C) ).

specific heat capacity equation

specific heat capacity (j/kg/⁰C) = change in internal energy (j) / (mass (kg) x maximum temperature rise (⁰C)

change in internal energy ( ΔE=mcΔθ ) equation

change in internal energy (kj) =mass (kg) × specific heat capacity (j/kg/°C)× temperature change (⁰C)

divide the answer by 1000 to turn it into kj

thermal heat capacity equation

thermal capacity=mass (kg) ×specific heat capacity (J/KG/°C)

Atmospheric Pressure

the force per unit of area created by the weight of the air (particles) in the atmosphere.

pressure equation

pressure (p)= force (N) / area (m²)

Liquid pressure

As you dive deeper into a swimming pool, there is more water (and weight) on top of you. This extra weight exerts a larger force (and higher pressure) on your body. The deeper down you swim, the more pressure you feel.

liquid pressure equation

Liquid pressure (p) = density (g/cm³) x gravitational field strength (N/kg) x depth (m)

depth underwater

Depth is equal to the height of the column of water above you.

baking bread

When you put bread in the oven, the temperature of the bread rises to 200°C. The air particles in the bread have more kinetic energy and exert pressure on the bread from the inside. This creates air bubbles that expand, causing the bread to rise.

force exerted by fluid

The force exerted on the surface in contact with the fluid particle will be at the normal to the surface (at right angles)

how snow shoes work

A snowshoe has a much wider surface area than a standard shoe. This means that for a person weighing 80kg, the pressure exerted (placed) on the snow is smaller if they wear snowshoes instead of trainers. This means that the person is less likely to sink into the snow.

Temperature of gases

As you heat a gas, you transfer more kinetic energy to the gas' particles.

pressure of gasses

• A gas exerts pressure on the walls of its container.

• There are lots of gas particles colliding with the container each second.

• When a gas particle collides with the wall of its container, its momentum changes and it bounces back off the wall.

• This exerts a force on both the particle and the wall.

• The pressure exerted on the wall is equal to the force (of the ball) per unit area (of the wall being hit).

momentum equation

momentum (kg/m/s) =mass(kg)×velocity(m/s)

an impulse

a change in momentum

constant equation

constant = pressure (p) x volume (m³)

hydraulic systems

These systems use fluids to transfer forces from one place to another. The pressure is the same throughout the system.