However, the same powder sprinkled in the open simply burns when ignited. In the confined state, the heat generated at the point of ignition will immediately ignite a large amount of surrounding material. Initiating explosives , the more sensitive of the two, must be handled with extreme care. They require only a low energy stimulus, such as being touched with a hot wire or tapped with a hammer, to explode. For that reason, they are put into blasting caps .
Secondary explosives are less sensitive and can burn without producing an explosion.
Since they are relatively stable, large amounts can be moved and handled safely. The velocity at which explosives detonate determines their function. Explosives of low detonating velocity supply a slow push or heave. Explosives with a high detonating velocity have a bursting or shattering effect. Propellant explosives are used for firearms, rockets, general engineering, and demolition work.