A race car traveling northward on a straight, level track at a constant speed travels 0.750km in 20.0s. The return trip over the same track is made in 25.0s. What is the average velocity of the car in m/s for the first leg of the run? What is the average velocity for the total trip?
By definition,
Average velocity = (displacement vector)/(elapsed time)
In the first case, there is a displacement of 0.75 km north.
In the second case, there is zero displacement. You end up where you started. 0/45 = ?
Trick question? Perhaps
To find the average velocity of an object, you need to divide the total displacement by the total time taken.
For the first leg of the run, the race car travels 0.750 km in 20.0 s. To find the average velocity in m/s, we first need to convert the distance from km to meters:
0.750 km = 750 m
Next, we divide the distance by the time:
Average velocity = Distance / Time = 750 m / 20.0 s
Calculating this, we find:
Average velocity = 37.5 m/s
Therefore, the average velocity of the car for the first leg of the run is 37.5 m/s.
For the total trip, we need to consider the displacement and total time taken for both legs. Since the car is returning over the same track, the total displacement is zero. In this case, the average velocity is simply the total displacement divided by the total time taken.
Total displacement = 0 km (or 0 m)
First leg time = 20.0 s
Second leg time = 25.0 s
Total time = 20.0 s + 25.0 s = 45.0 s
Average velocity = Total displacement / Total time = 0 m / 45.0 s
The average velocity for the total trip is:
Average velocity = 0 m/s
Therefore, the average velocity for the total trip is 0 m/s.