## Akoranga 4 Mahi Tuatahi

- Open Quizizz on your device (phone or laptop)
- Get ready to play!

https://quizizz.com/admin/quiz/5c110c53e13e0f001a388fbb/meteors-comets-and-asteroids

## Ngā Whāinga Ako

- Recall key terminology around meteorites
- Describe factors that affect the size and shape of an impact crater

Write the date and ngā whāinga ako in your book

## Pātai

- Do you recall the
**Law of Conservation of Energy**? Check with the person next to you!

### Whakatika

Energy cannot be created or destroyed, it can only be transferred or transformed.

## Pātai: Describe These Transformations

- Miles is playing football and kicks the ball into the air upfield to a striker.
- Toby gets up in the morning to go for a run. He eats three Weet-Bix before he goes.
- Phoenix goes bungee jumping near Wanaka.

Write the answers in paris, in your book.

### Whakatika

- Kinetic (foot) –> elastic + sound + heat –> kinetic + gravitational (ball) –> kinetic + sound + heat + pontential as the striker catches the ball.
- Chemical –> potential + kinetic as he gets up –> kinetic as he runs
- Potential –> kinetic –> elastic potential at the bottom

## Pātai: Energy in Meteors

What energy transformations do meteoroids undergo as they fall towards and onto a planet/moon?

### Whakatika

- In space they have gravitational potential & kinetic energy
- As they fall, gravitational potential energy is transformed into more kinetic energy
- Some of this kinetic energy is dissipated as heat/light/sound as it impacts the atmosphere

## Pātai

What happens to the rest of the kinetic energy if the meteor doesn’t completely break up in the atmosphere?

### Whakatika

The kinetic energy is transferred into the ground, creating an impact crater and throwing out debris!

## Gravitational Potential Energy / *Pūngao tō ā-papa*

The potential an object has to fall in a gravitational field.

\begin{aligned}
E_{p} &= mass \times gravity \times height \

E_{p} &= m \times g \times h
\end{aligned}

Pātai: What can we change about a meteoroid to give it more gravitational potential energy?

### Whakatika

- Increase its mass
- Increase its height (distance away from Earth) in the gravitational field

## Kinetic Energy / *Pūngao Neke*

Energy an object in motion has

\begin{aligned}
Energy &= \frac{1}{2} mass \times velocity^{2} \

E &= \frac{1}{2}m \times v^{2}
\end{aligned}

Pātai: What can we change about a meteorite to give it more kinetic energy?

### Whakatika

- Increase its mass!

\begin{aligned}
E = \frac{1}{2} \times 10 \times 10^{2} = 500J \

E = \frac{1}{2} \times 20 \times 10^{2} = 1,000J
\end{aligned}

- Increase its velocity (has a greater effect)!

\begin{aligned}
E = \frac{1}{2} \times 10 \times 10^{2} = 500J \

E = \frac{1}{2} \times 10 \times 15^{2} = 1,125J
\end{aligned}

## Akoranga 5 Mahi Tuatahi

- Brainstorm some characteristics of a crater that could change depending on the energy of the impact?

### Whakatika

- Crater depth
- Crater width
- Amount/volume of debris ejected
- Distance that debris is ejected

## Conservation of Energy

Typically to increase the energy of an impact in a simulation we increase the height that it is dropped from, thereby giving it more gravitational potential energy to be converted to kinetic energy (increasing its impact velocity).

\begin{aligned}
E_{p} &= E_{k} \

m \times g \times h &= \frac{1}{2}m \times v^{2} && \text{Mass cancels out} \

g \times h &= \frac{1}{2} \times v^{2} && \text{Re-arrange for v} \

2 \times g \times h &= v^{2} \

\sqrt{2 \times g \times h} &= v
\end{aligned}

### Theoretical vs Real-World

\begin{aligned} v = \sqrt{2 \times g \times h} \end{aligned}

- This gives the
*theoretical*impact velocity of a rock dropped within Earth’s gravitational field. **Pātai**: What assumption are we making here?**Whakatika**: That energy is conserved**Pātai**: What happens to some of that energy?**Whakatika**: That some energy is lost to the atmosphere as light/heat/sound.**Whakakapi/Conclusion**: Real-world velocity is less than the theoretical maximum velocity.

## Pātai

\begin{aligned}
v &= \sqrt{2 \times g \times h} \

E_{k} &= \frac{1}{2} \times m \times v^{2}
\end{aligned}

- Calculate the impact speed of an object dropped from $1m$
- Calculate the impact speed of an object dropped from $2m$
- Calculate the impact speed of an object dropped from $5m$
- Calculate the impact kinetic energy of a $10kg$ object travelling at $3000ms^{-1}$
- Calculate the impact kinetic energy of a $750kg$ object travelling at $5000ms^{-1}$

## Ngohe: Google Earth Tour

- Open Google Classroom and find the Google Earth link
- Follow through the tour – make sure to
**read more**on each stop!

## Ngohe: Quizizz

https://quizizz.com/admin/presentation/5fcd762e8e241c001b80de03/meteoroids-meteor-or-meteorites