In some states, the highway patrol uses planes carrying radar devices to monitor traffic. as the plane flies over traffic, the radar device can tell the officers how fast each car is moving at that moment in time. the radar device determines the car's

Radar is a highly upgraded electromagnetic device or technology that helps in determining where an object is located, at what distance it is, and also determines the speed and direction at which an object is moving, and at what angle it is.

It is generally used by the traffic police, for controlling the speed limit of a vehicle or motorbikes in any countries.

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.