The slope of a line on a distance time graph represents what

The speed of an object is denoted by a distance time graph.

Explanation:

The speed of an object is calculated on the basis of distance travelled in per unit of time. The distance and time graph's  gradient shows the speed of the object.  Distance is referred to as measure of the path between two points. Displacement is the vector quantity that measures distance with a line that is straight in nature.

The velocity of the object is represented as the speed by which the object moves in a particular direction. The acceleration of the object can be measured by a velocity - time graph.

answer; i believe the correct answer is (a)0

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.