# Velocity When a Runner Covers Half a Lap

• Bottomsouth
In summary, the runner covered one lap of a circular track with a diameter of 40.0 meters in 63.2 seconds. Her average velocity for the first half-lap, which she completed in 28.7 seconds, was 1.4 meters per second. This is calculated by dividing the displacement of 40 meters by the time of 28.7 seconds.
Bottomsouth

## Homework Statement

A runner covers one lap of a circular track 40.0 in diameter in 63.2 .

If she covered the first half-lap in 28.7 , what were her average velocity for that half-lap?

## Homework Equations

We use perimeter of a cirle = 2*3.14*20m to get 125.6

## The Attempt at a Solution

I know that if the runner runs around a full lap, he or she will be at 0 velocity. But at half a lap I tried 62.8/28.7 to get 2.188. I am sure that is the speed and not the answer. I know I am making a small mistake.

Hint: Average velocity is the change in displacement (a vector) divided by the change in time. So what's the change of the runners dsplacement, both in magnitude and direction?

No ideas? 1?

I gave you the hint. Take it from there.

the runner ends in the same place he/she starts.

dnp33 said:
the runner ends in the same place he/she starts.
After one lap, she does, but not after half a lap.

haha.

Got it, 1.4 m/s because displacement is the shortest distance. This would be 40 m / 28.7 s.

## 1. What is the formula for calculating velocity when a runner covers half a lap?

The formula for calculating velocity is velocity = distance / time.

## 2. How do you convert the distance covered by a runner in half a lap to meters?

To convert the distance covered by a runner in half a lap to meters, you need to know the length of the track. Then, you can multiply the distance by the appropriate conversion factor. For example, if the track is 400 meters, the distance covered by the runner in half a lap would be 200 meters.

## 3. Is velocity the same as speed?

No, velocity and speed are not the same. Velocity is a vector quantity that includes both magnitude (speed) and direction, while speed is a scalar quantity that only measures the magnitude of an object's motion.

## 4. What units are typically used to measure velocity?

Velocity is typically measured in meters per second (m/s) or kilometers per hour (km/h).

## 5. Can a runner have a negative velocity when covering half a lap?

Yes, a runner can have a negative velocity when covering half a lap if they are running in the opposite direction of the positive direction, or if their velocity is decreasing over time.

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