There is NOT a difference in speed between a car going forwards at 5 m/s and a car moving backwards at 5 m/s.
Speed is just the rate of change of the position of an object. It is calculated by dividing the change in position (distance traveled) by the time it takes to move said distance.
The distance between the two points is always positive because the direction does not matter.
However, if we are looking for the velocity, the direction DOES matter. In this example, the velocity moving forwards is 5 m/s while the velocity moving backwards is -5 m/s.
In other words:
<em>Speed </em>is looking at the <em>magnitude</em>
<em>Velocity </em>is looking at the <em>magnitude </em><em>and </em><em>direction.</em>
Answer:
Xylem cells have no cytoplasm or end walls, meaning they form a tube through which water can pass freely to allow water transport. Lignin strengthens the cell walls, helping to support the plant.
<u>The right answers are:</u>
HOX genes are very similar in all animals.
Many species share much the same DNA.
Plant and animal cells have almost all of the same structures.
