During use, the springs are arranged at the bottom of the shoe pad, so that when children jump, the shoe has the buffer action and protects the joints of the legs and the knees of children; and when the children jump, the loudspeaker can make a sound and the lighting lamp can emit ...
aWith radar,however,the waves are radio waves instead of sound waves.Radio waves travel at the speed of light,about 300,000 kilometers in one second.A RADAR SET SENDS OUT A SHORT BURST OF RADIO WAVES.Then it receives the echoes produced when the waves bounce off objects.By determining ...