19,879
edits
Changes
→Key Stage 3
|-
| style="height:20px; width:400px; text-align:center;" |The equation for '''gravitational potential energy''' written in symbols.
|}
===Calculating Gravitational Potential Energy===
{| class="wikitable"
| style="height:20px; width:200px; text-align:center;" |A weight lifter lifts a 50kg [[mass]] a distance of 2.0m from the ground. Calculate the increase in '''gravitational potential energy''' of the [[mass]].
g on Earth is 9.8N/kg
| style="height:20px; width:200px; text-align:center;" |A pulley is used to lift a 12 tonne [[mass]] 0.80m above the ground. Calculate the change in energy in the '''gravitational potential store'''.
g on Earth is 9.8N/kg
Give your answer correct to two [[Significant Figures|significant figures]].
| style="height:20px; width:200px; text-align:center;" |During a rock slide a 320kg boulder falls from a [[height]] of 1450m to a [[height]] of 730m above sea level. Calculate the change in '''gravitational potential energy'''.
g on Earth is 9.8N/kg
Give your answer correct to two [[Significant Figures|significant figures]].
|-
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
m = 50kg
g = 9.8N/kg
Δh = 2.0m
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
m = 12tonne = 12,000kg
g = 9.8N/kg
Δh = 0.80m
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
m = 320kg
g = 9.8 N/kg
Δh = h<sub>2</sub> - h<sub>1</sub> = 1450 - 730 = 720m
|-
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
<math>E_g = m g \Delta h</math>
<math>E_g = m \times g \times \Delta h</math>
<math>E_g = 50 \times 9.8 \times 2</math>
<math>E_g = 980J</math>
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
<math>E_g = m g \Delta h</math>
<math>E_g = m \times g \times \Delta h</math>
<math>E_g = 0.80 \times 9.8 \times 12000</math>
<math>E_g = 94080J</math>
<math>E_g \approx 94000J</math>
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
<math>E_g = m g \Delta h</math>
<math>E_g = m \times g \times \Delta h</math>
<math>E_g = 320 \times 9.8 \times 720</math>
<math>E_g = 2257920J</math>
<math>E_g \approx 2300000J</math>
|}