1. Kinetic energy

2. Learning objectives Describe the factors that affect kinetic energy
Perform calculations involving kinetic energy

3. What is the difference? Dropping a piece of paper on your head
Dropping a car on your head

4. What is the difference? Driving into a car at 5km/h

5. Graph to show the relationship between kinetic energy and velocity
Draw a graph to show the following data
What do you notice about the shape of the graph
Car velocity (m/s)
Kinetic energy (J) 1
750 2
3000 3
6750 4
12000 5
18750 6
27000 7
36750 8
48000 9
60750 10
75000

6. Graph to show the relationship between mass and velocity
Draw a graph to show the following data
What do you notice about the shape of the graph
Mass of falling animal (kg)
Kinetic energy at 10m/s (J)
1g (spider)
.05
45g (mouse)
2.25
500g (hedgehog) 25
2kg (cat)
100
50kg (large dog)
2500
150kg (panda)
7500
800kg (horse)
40^000

7. Factors affecting kinetic energy
Which 2 variables affect kinetic energy?
Which has the most effect
What could the formula be?

8. Factors affecting kinetic energy
Both mass and velocity affect kinetic energy
Velocity has the most effect – as you double the velocity, you quadruple the energy
The formula is KE = ½mv2

9. Practical You will run 5m. This will be timed
This will tell us the average velocity
We can then work out how much KE you had if you know your mass
My mass
My time for 5 metres
Average velocity (5 / time)
Kinetic energy

10. Questions
An 1900kg elephant falls off a building at 8m/s. Calculate the KE
How fast would a 60g mouse have to travel to have the same KE? m/s and km/h
Calculate the KE of an 11g bullet travelling at 230m/s
Calculate the KE of a bob sled and rider (82kg) travelling at 118km/h

11. Questions
An 1900kg elephant falls off a building at 8m/s. Calculate the KE
.5 x 1900 x 82 = 60.8kJ
How fast would a 60g mouse have to travel to have the same KE?
60800 = ½mv2 v=√60800/½ v=1424m/s (5100km/h)
Calculate the KE of an 11g bullet travelling at 230m/s
½ x x = J
Calculate the KE of a bob sled and rider (82kg) travelling at 118km/h
118km/h = m/h = /3600 = 32.77m/s
KE= ½ x 82 x = kJ

12. Learning objectives Describe the factors that affect kinetic energy
Perform calculations involving kinetic energy