Energy Stores
State the law of conservation of energy
Energy cannot be created or destroyed
What are the units for Gravitational Potential energy?
Joules
What is the equation for calculating KE?
KE = 0.5 x m x v2
batteries, food and fuels are what type of energy store?
Chemical energy store
What is the equation for GPE? Include units
GPE = m x g x h
(mass (kg) x gravitational field strength (N/kg) x height (m))
In the Elastic potential equation, what does the 'k' stand for?
spring constant, N/m
What are the 5 energy stores?
Thermal, Kinetic, Chemical, Gravitational Potential and Elastic Potential energy
What is the value for gravitational field strength on Earth? Include units
10 N/kg
Calculate the KE of a vehicle with mass of 500kg and a speed of 20m/s
KE = 0.5 x m x v2
KE = 0.5 x 500 x 202
KE = 100,000J
What are the 4 means of energy transfer?
Heating, Waves, Electricity and Force
Calculate GPE of a ball on Earth if:
mass = 5kg
height = 5m
GPE = m x g x h
GPE = 5 x 10 x 5
GPE = 250J
EE = 0.5 x k x e2
EE = 0.5 x 200 x 82
EE = 6,400 J
A diver stands on top of the diving board. They then jump into the water.
Describe the scenario in terms of energy stores and transfers.
The gravitational potential energy store is transferred to kinetic energy store by force
A student weight 450N steps on a box of height 0.2m. Calculate the increase in GPE store.
GPE = m x g x h
m x g = 450N
GPE = 450 x 0.2
GPE = 90J
Calculate the velocity of runner if they have a kinetic energy of 6000J and a mass of 80kg.
KE = 0.5 x m x v2
6000 = 0.5 x 80 x v2
v2 = 6000 / 40
v = 12.25 m/s