2. When a shot is fired from a piece, by how many forces is it acted on?
By three.—1st. The impulsive force of the powder, which urges it forward.
2d. The resistance of the air, which tends to stop it.
3d. The force of gravity which causes it to descend.
3. Why is it necessary to give a certain degree of elevation to a piece?
Because a shot describes under the action of the above forces a curve called a trajectory, which is situated below the prolongation of the axis of the piece, the extent of its departure from this line increasing with the time of flight. Therefore, the more distant the object, the greater must be the elevation to enable the shot to reach it.
4. How is the direction given to a gun or howitzer?
By directing the line of metal upon the object.
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5. How is the elevation or depression given?