Energy

Question 1

What is a system?

Answer 1

A system is an object or group of objects.

Question 2

What is the equation for kinetic energy?

Answer 2

½mv²
½ × Mass × (Velocity)²
Energy (J), Mass (kg), Velocity (m/s)

Question 3

What is the equation for elastic potential energy?

Answer 3

½ke²
½ × Spring Constant × (Extension)²
Energy (J), Spring Constant (N/m), Extension (m)

Question 4

What is the equation for gravitational potential energy?

Answer 4

mgh
Mass × Gravitational Field Strength × Height
Energy (J), Mass (kg), Gravitational Field Strength (N/kg), Height (m)

Question 5

What is specific heat capacity and what are the units of shc?

Answer 5

The amount of energy needed to increase the temperature of 1kg of a substance by 1°C.
J/°C/kg
Joules/Degree Celsius/Kilogram

Question 6

What happens when an object is projected upwards (flying)?

Answer 6

• When an object is projected upwards, such as a ball, it will initially have kinetic energy.
• As the object rises higher into the air, the kinetic energy will be transferred into gravitational potential energy.
• Once the object reaches its highest point, the gravitational potential energy will all be converted into kinetic energy as the object falls back to the ground.

Question 7

What happens when a moving object hits an obstacle (collision)?

Answer 7

• A moving object will start off with kinetic energy.
• Once it hits an obstacle, the kinetic energy can be transferred into many different types of energy.
  
  • It can be transferred to the surroundings as
    thermal energy and sound waves.
• Some of the kinetic energy of the moving object can even be transferred to the obstacle, causing it to move.

Question 8

What happens when an object accelerates by a constant force (acceleration)?

Answer 8

• When an object is accelerated by a force, there is a transfer of energy.
• Firstly, energy is required to accelerate the object; this could be chemical, thermal or electrical (the situation will determine the specific type of energy).
• This energy will then be converted into kinetic energy (used to accelerate the object).

Question 9

What happens when a vehicle slows down (deceleration)?

Answer 9

• To slow down the vehicle, the kinetic energy of the movement will be transferred into another store of energy.
  
  • This energy could be sound waves and thermal
    energy.

Question 10

What happens when you bring water to a boil in an electric kettle (heating)?

Answer 10

• When we are heating up water in an electric kettle, we are transferring electrical energy into thermal energy.
  
  • Which is used to heat up the water.

Question 11

What is the definition and unit of power?

Answer 11

The rate at which energy is transferred (or rate at which work is done).

Watt (W)

Question 12

What are two equations for power?

Answer 12

power = energy transferred/time
power = work done/time

Energy (J), Work Done (J), Time (s)

Question 13

State all the 8 different energy stores?

Answer 13

• Kinetic Energy
• Chemical Energy
• Gravitational Potential Energy
• Elastic Potential Energy
• Thermal Energy
• Electrostatic Energy
• Nuclear Energy
• Magnetic Energy