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# Submarine buoyancy

This activity sees students use modelling clay, coins or other masses to make a ping pong ball neutrally buoyant. Student will learn that neutral buoyancy is achieved when the ball is maintaining a constant depth.

Broadcast on Thu 28 Mar 2019
• 45 mins
• Ages 7-11, Ages 11-14
##### Preparation

Prepare your resources, each group will need, modelling clay (suggested), small masses, small coins, ping pong ball, tape if using coins or slotted masses, ice cream tub or similar deep container and access to a digital balance. Before the investigation begins ensure your container is filled with water.

##### Session steps

1. Introduction (5 mins)
Jamie will open the session with a welcome and brief introduction to the expedition and any shout-outs to registered classes. In this activity students will begin to understand the property of neutral buoyancy and its importance in terms of submarines.

2. Subject knowledge (5 mins)
Jamie will then explain that this practical activity explores the mathematics of density, forces and buoyancy.

3. Activity time (15 mins)
Jamie will then begin demonstrating the activity and students can follow along in real-time. The practical investigation involves dropping ping pong balls into the container. Initially the ping pong ball is dropped in the water and it should float. It is then up to the students to add weight to the ball using the clay (or by taping coins or weights to the ball). They then need to test to see if it continues to float. If the ball sinks, students should remove some weight and try again. If the ball floats, then add more weight. Remember the aim of the investigation is to make the ball neutrally buoyant. This will be achieved when the ball is maintaining a constant depth without sinking to the bottom.

At this point, you can submit your students’ questions via the live chat.

4. Q&A and conclusion (20 mins)
After completing the activity Jamie will be able to answer pre-submitted questions and take part in the live chat. At the end of the broadcast, Jamie will suggest some other activities you might like to try and what's coming up in the rest of Submarine Live 2019.

## Speakers

Jamie Buchanan-Dunlop

Executive Director, Encounter Edu

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