A constant force is a force that does not change in size or direction for a period of time; The displacement of the object under the action of a constant force in the direction not perpendicular to the action line of the constant force (not necessarily caused by the action of the constant force) indicates that the constant force does work, and the magnitude of the work W=| F | | s | cos<F, s>(F, s is a vector), where | s | cos<F, s>is the distance the object passes in the direction of the constant force. Take throwing an object horizontally to the right as an example. The trajectory of the object is a parabola. 1. Make a straight line coincident with the speed direction of the object at the initial position; If the initial velocity direction of the object is horizontal, the straight line made is a horizontal line.
Citation explanation
Take throwing an object horizontally to the right as an example. The trajectory of the object is a parabola
1. Make a straight line coincident with the speed direction of the object at the initial position;
If the initial velocity direction of the object is horizontal, the straight line made is a horizontal line
2. Look at the bending of the moving track of the object, then the direction of the resultant external force on the object is on the side of the straight line with track;
The object is obviously downward, that is, the end of the object with track is below the horizontal line made in 1, not above
3. In the same way, the direction range of the external force and the force on the object at the end position is determined. Translate the two ranges together, and the common area is the direction range of constant force.
The speed of the object at the end position is oblique downward. If you make another straight line, it will also be a oblique downward straight line
Then one end of the trajectory is the left side of the diagonal line, and the common area of the two ranges is the range contained by the parabola.
This object is subject to only one constant force (regardless of air resistance ）, that is, gravity Gravity direction is Vertical Down Within the public area. Constant force is gravity, which is in the same direction as gravity.
