This is a simple physics question. But i dont understand what's the difference of speed and velocity here.

Question

Town A and Town B are 100 meters apart. A car travels from Town A to Town B in 2 hours. Then , the car travels back to Town A from Town B in 3 hours.

What is the velocity of this trip after 5 hours?

Answer 1

The velocity is 0!

Velocity is defined as "change in distance over a change in time". The net change in distance after 5 hours is 0. Therefore, the velocity is 0m/5hr = 0m/hr.

Answer 2

This problem is very poorly worded, so we'll have to make some assumptions.

* I assume the towns are really 100 km apart, not 100 meters.
* A "trip" does not have velocity. I assume what is meant is, "the velocity of the _car_".
* There's "average velocity" and there's "instantaneous velocity," which are two different things. Normally the word "velocity" by itself implies the "instantaneous" kind; however, there's no way to determine instantaneous velocity from the information given; so I'll assume the author meant to say, "average velocity".

Now that that's out of the way:

Normally in a problem like this, what you're really after is average _speed_, and you can ignore the technical distinction between speed and velocity. However, it sounds like the asker is interested in that technical distinction. So let's assume that what is wanted really is "velocity" as the problem states (and not "speed"). So:

To find the average velocity, you have to measure the object's position at two points in time. Then:

1. Draw a straight line stretching from the first position to the 2nd position;
2. Measure the length of the line;
3. Divide the length of the line by the elapsed time. This will give you the magnitude (the amount) of the average velocity.
4. The direction of the average velocity is the direction that the line is pointing.

In this problem, the length of the line (in Step 2) is zero, since the ending location is the same as the beginning location. That means that the average velocity is zero.

Now, if what you want is actually the average _speed_, that is found somewhat differently. In that case, you measure the total distance that the object travels (in this case, 200 km), and divide that by the total time (5 hours).

Answer 3

Speed is magnitude of displacement/time, a scalar quantity.
Velocity is magnitude and direction of displacement/time, a vector quantity.

You cannot state a velocity because you don't know any directions. Somebody (not you) is an idiot. More than likely more than one.

Two towns a re 100 meters apart? That's a football field. It can be run on foot in under 10 seconds.

Answer 4

The question seems to refer to the velocity for the whole trip. While speed is distance/time with no particular direction, velocity is speed in a given direction.
Since the trip went 100 meters in one direction & returned, the direction factor is zero. Therefore the velocity for the trip is zero.

Answer 5

You have stated it incorrectly - I suspect it is kilo-meters, rather than meters. and the answer is extremely simple. Velocity = 200 Km / 5 hours = 40 KM / hr...

average velocity is total distance divided by total time. v = s/t... Miles per Hour, distance divided by time...

Shame on you. And "velocity" is the "official" term, but means the same as speed in this simple example. Read you text book!

PS - "velocity" does not become a vector until later classes. And in those later classes you will never see that 100KPH north, followed by 100KPH sourth results in a velocity of zero. That is silly. The "vector" is for things like colisions, and angle of incidence to calculate the velocity vector of an object that is hit (pool table).

Ron.

Answer 6

The average speed of the trip would be 200m/5hr or 40m/hr. There is no direction in the definition of speed.
The definition of velocity also contains a direction component. Therefore since the car is back where it started, the average velocity of the trip is 0

Answer 7

Velocity is distance/time

so for total trip : velocity must be : 200m / 5 hr = 40 m/hr


Total Distance = 100 + 100
Total Time = 2 + 3

Answer 8

It would appear to be 40 meters.

First off, you probably meant kilometers?
Anyway.....

The car has traveled 200 meters round trip in 5 hours, a very slow car.
200/5=40 or 40 meters per hour right?

Answer 9

The question can be misleading at first, but by the term "velocity", it is actually asking about the sum of the vector velocities.

If Town A is the origin, then:

V1 = 100 / 2 = 50 m/hr
V2 = -100 / 3 = -33.3 m/hr

Therefore:

V = V1 + V2 = 50 + (-33.3) = 16.7 m/hr.

Answer 10

The speed is the average of the rates of movement 200m/5h = 40m/h.

The velocity it the chance of position divided by time. Since the car is where is started, the distance, and thus velocity, is zero.