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Experiments with Water (Smart Dead Sea Salinity & Buoyancy Lab)

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Explore why objects sink in fresh water but float in salt water! Place a toy figure in fresh water (it sinks!). Add salt to the jar; a TDS salinity probe measures PPM while an ultrasonic sensor tracks rising float levels.

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Props & Materials Required

  • •2 clear water testing jars (Fresh Water & Salt Water)
  • •Analog TDS (Total Dissolved Solids) / Salinity sensor probe
  • •HX711 load cell buoyant force sensor
  • •Toy swimmer figure with metallic weight
  • •ESP32 controller board
  • •0.96-inch OLED display screen
  • •DFPlayer Mini MP3 module + 3W speaker

Step-by-Step Instructions

1

Drop Figure in Fresh Water

Drop toy swimmer in fresh water jar. Figure SINKS to the bottom. TDS probe reads '100 PPM'.

2

Add Salt to Water Jar

Stir 4 spoons of salt into the water. Dissolved salt increases water density!

3

Read Salinity & Watch Figure Float

TDS probe reads '25,000 PPM (DEAD SEA SALINITY!)'. The toy swimmer POP-UP FLOATS to the top surface!

4

Buoyancy Science Audio Explanation

OLED displays 'Buoyant Force > Gravity Force!'. Speaker: 'Salt increases water density! In the Dead Sea, humans float effortlessly without swimming!'

Why It Works & Notes

Experiments with Water explores why lemon/eggs sink in plain water but float in salt water, culminating in the Dead Sea phenomenon. Measuring salinity (TDS) as salt dissolves and observing buoyant force changes makes physics crystal clear.