# Separate Physics - 6.1 Flashcards

In physics, what is a ‘system’?

A system is an object or group of objects

What changes are involved in the way energy is stored in an object projected upwards?

Chemical Energy → Kinetic Energy → Gravitational Potential Energy

What changes are involved in the way energy is stored in a moving objecting hitting an obstacle?

Kinetic Energy → Sound Energy / Thermal Energy

What changes are involved in the way energy is stored in an object accelerated by a constant force such as gravity when dropping a ball?

Gravitational Potential Energy → Kinetic Energy

What changes are involved in the way energy is stored in a vehicle slowing down?

Kinetic Energy → Heat Energy

What changes are involved in the way energy is stored bringing water to a boil in an electric kettle?

Electrical Energy → Thermal Energy

What equation is used to calculate the kinetic energy of a moving object?

How can the gravitational potential energy gained by a raised object above the ground be calculated?

What is the specific heat capacity of a substance?

The amount of energy required to raise the temperature of 1kg of the substance by 1^{o}C

What is power?

The rate at which energy is transferred / the rate at which work is done

What are the three equations associated with power?

What energy transfer is equal to a power of 1 watt?

1 joule per second

Lifting an object takes 10’000J – machine A can do this in 50s but machine B takes 100s. Which machine is more powerful?

Both machines transfer the same amount of energy, but machine A is more powerful:

P = W ÷ t

Machine A has a power of 200W (10’000 ÷ 50) whilst machine B has a power of 100W (10’000 ÷ 100)

What is the conservation of energy principle?

Energy can be transferred usefully, stored or dissipated but never created or destroyed

What happens to the energy transfer in a closed system?

There is no net change to the total energy

When energy is transferred not all of it is transferred usefully (some energy is dissipated). What term is used to describe this dissipated energy?

Wasted energy

How does lubrication reduce unwanted energy transfers?

Lubrication reduces frictional forces