Principle of gear shuttle: Chemical energy in the battery is converted into kinetic energy of the motor. The motor drives the driving gear to rotate. When the driving gear touches the ground,...
Product Name: Science and Technology Small Production: Earthquake Alarm
Weight: about 55g
Dimensions: 8*6*12.5cm
Packing: opp self-sealing bag
General knowledge of seismograph: In 132 AD, Zhang...