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→Calculating Velocity from Kinetic Energy
v = The [[speed]] or [[velocity]] of the [[object]].
===Calculating Kinetic Energy===
{{#ev:youtube|https://www.youtube.com/watch?v=D-eCSsnFEy0}}
{| class="wikitable"
| style="height:20px; width:200px; text-align:center;" |A 700kg formula one racing car has a top speed of 100m/s. Calculate the '''kinetic energy''' of the [[car]] to two [[Significant Figures|significant figures]].
| style="height:20px; width:200px; text-align:center;" |A cheetah of mass 75kg runs at a speed of 32m/s. Calculate the '''kinetic energy''' of the cheetah correct to two [[Significant Figures|significant figures]].
| style="height:20px; width:200px; text-align:center;" |A 160g cricket ball is hit at 44m/s. Calculate the '''kinetic energy''' of the cricket ball correct to two [[Significant Figures|significant figures]].
|-
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
m = 700kg
v = 100m/s
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
m = 75kg
v = 32m/s
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
m = 160g
'''Convert [[mass]] into [[kilogram]]s.'''
m<sub>in kilograms</sub> = <math>\frac{160}{1000}</math>
m = 0.16kg
v = 32m/s
|-
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
<math>E_k = \frac{1}{2} m v^2</math>
<math>E_k = \frac{1}{2} \times 700 \times 100^2</math>
<math>E_k = \frac{1}{2} \times 700 \times 10,000</math>
<math>E_k = 3,500,000J</math>
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
<math>E_k = \frac{1}{2} m v^2</math>
<math>E_k = \frac{1}{2} \times 75 \times 32^2</math>
<math>E_k = \frac{1}{2} \times 75 \times 1024</math>
<math>E_k = 38,400J</math>
<math>E_k \approx 38000J</math>
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
<math>E_k = \frac{1}{2} m v^2</math>
<math>E_k = \frac{1}{2} \times m \times v^2</math>
<math>E_k = \frac{1}{2} \times 0.16 \times 44^2</math>
<math>E_k = \frac{1}{2} \times 0.16 \times 1936</math>
<math>E_k = 154.88J</math>
<math>E_k \approx 150J</math>
|}
===Calculating Velocity from Kinetic Energy===