P1 - Conservation and Dissipation of Energy

What is a Chemical Energy Store?

Fuels

Foods

Chemicals found in Batteries

What is Kinetic Energy?

The energy an object has because it’s moving.

What is a Chemical Energy Store?

Fuels

Foods

Chemicals found in Batteries

What is Kinetic Energy?

The energy an object has because it’s moving.

What is Gravitational Potential Energy?

The energy an object has because of its position.

What is Elastic Potential Energy?

The energy stored in a springy object when stretched or squashed.

What is Thermal Energy?

The energy a substance has because of its temperature.

Why do moving objects typically transfer some energy to their surroundings?

Because of air resistance and friction.

In which case/environment is this not true? Explain Why.

In a vacuum. This is because there is no air in a vacuum: therefore, there would be no air resistance which would cause a moving object to transfer energy to their surroundings.

What is a Closed System?

A Closed System is a system where there is no net change to the energy stored.

State The Law of Conservation of Energy.

The Law of Conservation of Energy is:

Energy can not be created or destroyed.

What is Energy Transferred the same as?

Energy Transferred = Work Done

What is the equation for work? Give symbols and units.

Work Done = Force Applied x Distance Moved

W = F x s

(Joules, J) = (Newtons, N) x (Metres, m)

What happens to the Gravitational Potential Energy Store when an object is moved upwards?

When an object is moved upwards, GPE increases.

What happens to the Gravitational Potential Energy Store when an object is moved down?

When an object is moved down, GPE decreases.

State the equation for Change in GPE store.

Change in GPE Store = weight x change of height

(Joules, J) = (Newtons, N) x (metres, m)

State the equation for Change in GPE store when gravitational field strength is taken into account.

Change of GPE Store = mass x gfs x change of height

ΔEp = m x g x Δh

(Joules, J) = (kilograms, kg) x (newtons per kilogram, kg) x (metres, m)

State the equation for Kinetic Energy.

Kinetic Energy = ½ x mass x speed²

Ek = ½ x m x v²

(Joules, J) = ½ x (kilograms, kg) x (metres per second, m/s)²

State the equation for Elastic Potential Energy.

Elastic Potential Energy = ½ x Spring Constant x Extension²

Ee = ½ x k x e²

(Joules, J) = ½ x (Newtons per Metre, N/m) x (metres, m)²

What is Useful Energy?

Useful Energy is energy transferred to where it is wanted in the way it is wanted.

What is Wasted Energy?

Wasted Energy is the energy that is not usefully transferred - usually dissipates to surroundings.

How do you figure out Input Energy?

Input Energy = Useful Output Energy + Energy Wasted

(energy supplied, J) = (J) + (J)

What is the equation for Efficiency?

Efficiency = Useful Output Energy / Total Input Energy

(%) = (J) / (J)

What is the Measurement for:

1. Weight

2. Energy

The measurements for:

1. Weight is newtons

2. Energy is joules

How do you reduce these energy waste problems?

1. Friction between the moving parts causes heating.

2. Resistance of a wire causes the wire to get hot when a current passes through it.

3. Air resistance causes a force on a moving object that opposes its motion.

4. Sound created by machinery causes energy transfer to the surroundings.

What is the Useful Energy and Wasted Energy for these daily appliances?:

1. Light Bulb

2. Electric Heater

3. Electric Toaster

4. Electric Kettle

5. Hairdryer

6. Electric Motor

The energy you apply to something per second is the same as…?

The energy you apply to something per second is the power supplied to it.

1W = 1J/s

Therefore, the more powerful an appliance is…

Therefore, the more powerful an appliance is, the faster the rate at which it transfers energy.

What is the equation for power?

Power = Energy Transferred / time taken

P = E/t

(Watts, W) = (Joules, J) / (seconds, s)

How do you calculate power wasted?

Power Wasted = Total Power In - Useful Power Out