year 9 science - energy

Question 1

state the law of conservation of energy

Answer 1

energy cannot be created or destroyed, but rather transformed from one form to another, with the total amount of energy in a closed system remaining constant

Question 2

energy efficiency formula

Answer 2

efficiency=(useful energy output/total energy input)x100

Question 3

ohms law formula and what it means

Answer 3

V = I x R
V is voltage (V)
I is current (A)
R is resistance (Ω)

Question 4

power formula

Answer 4

P = W/T
P is power (Watts)
W is work (J)
T is time (s)

OR

P = V x I
P is power (watts)
V is voltage (V)
I is current (A)

Question 5

elements of a complete circuit

Answer 5

• conductive path (wires)
• power source (battery)
• load (resistors, light bulb etc.)

Question 6

series vs parallel circuits

Answer 6

series - one path for current
parallel - multiple paths for current

Question 7

non-renewable energy sources

Answer 7

• coal
• oil
• natural gas
• nuclear

Question 8

renewable energy sources

Answer 8

• solar
• wind
• hydro
• geothermal (heat within the earth eg. hot springs, volcanoes)
• biomass (plants)

Question 9

ways to improve energy efficiency

Answer 9

• use energy efficient appliances (star rating)
• reduce energy waste (turn off unused devices)
• improve insulation in buildings
• use renewable energy sources

Question 10

kinetic energy formula
*the faster something moves the more kinetic energy it has

Answer 10

KE = 1/2 mv²
KE is kinetic energy (Joules)
m is mass (kg)
v is velocity (minutes/second)
so therefore, kinetic energy = half of (mass x velocity squared)

Question 11

gravitational potential formula
*higher objects have more potential energy

Answer 11

GPE = mgh
GPE is gravitational potential energy
m is mass (kg)
g is gravity (9.8m/s²)
h is height (m)

Question 12

kinetic vs potential

Answer 12

KE = energy of movement
PE = stored energy due to position

Question 13

TYPES OF ENERGY (there are 11 (three potential energies)

Answer 13

1. Kinetic energy
2. Potential energy
   - gravitational potential energy
   - elastic potential energy
   - chemical potential energy
3. Thermal energy
4. Electrical energy
5. Light energy
6. Sound energy
7. Nuclear energy
8. Mechanical energy

Question 14

mechanical energy formula

Answer 14

ME = KE + PE