## Time Velocity And Speed

- Explain the relationships between instantaneous velocity, average velocity, instantaneous speed, average speed, displacement, and time.
- Calculate velocity and speed given initial position, initial time, final position, and final time.
- Derive a graph of velocity vs. time given a graph of position vs. time.
- Interpret a graph of velocity vs. time.

Figure 1. The motion of these racing snails can be described by their speeds and their velocities.

There is more to motion than distance and displacement. Questions such as, How long does a foot race take? and What was the runners speed? cannot be answered without an understanding of other concepts. In this section we add definitions of time, velocity, and speed to expand our description of motion.

## Average Speed And Average Velocity

Before learning about average speed and average velocity, we must know the difference between distance and displacement.

Distance is a scalar quantity which generally implies how much ground has been covered by the object. On the other hand, displacement is a vector quantity, and it is the shortest possible distance between the start and end point.

Example: If a particle is moving in a circle, after one revolution, the distance will be the perimeter of the circle while the displacement would be zero.

Now, let us see what speed and velocity actually are.

**Speed:** Speed is a scalar quantity which means it has no direction. It denotes how fast an object is moving. If the speed of the particle is high it means the particle is moving fast and if it is low, it means the particle is moving slow.

**Velocity:** Velocity is a vector quantity which means it has both magnitude and direction. It denotes the rate at which the object is moving or changing position. The direction of the velocity vector is easy to find. Its direction is same as the direction of the moving object. Even if the object is slowing down, and the magnitude of velocity is decreasing, its direction would still be same as the direction in which the object is moving

## How To Use The Formula For Average Speed

To understand how to use the formula for average speed let us consider an example.Example: A runner completes a 100m lap in 40 sec. After the finish of the first lap, he reached back to the starting point. Calculate the average speed of the runner.Solution: Total distance covered by the runner = 100 metersTotal time = 40 sec

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## Difference And Examples Of Average Speed And Average Velocity

To know about average speed and average velocity, first we must know of some terms and their meanings.

Distance Travelled Distance travelled, as the name clearly tells, is the total distance travelled by the object.

Time Taken The time taken by the object to move the given distance.

Displacement Displacement is the shortest distance between the initial point where the object was and the final point where the object ended up.

Speed Speed is the distance travelled by an object in unit time. Speed is a scalar quantity. This means it has no specified direction. Speed refers to how fast an object is moving, or essentially the rate at which the distance is covered.

Velocity Velocity is the total displacement of the object in a specified direction in unit time. Velocity is a vector quantity. This means it has a specified direction. Velocity refers to the time rate of displacement of the object. Imagine a person who walks for some distance before returning to his original position. Since velocity is the rate of displacement, this motion results in zero velocity. If a person wishes to maximise his velocity, he must maximise the displacement from his original position. Since velocity is a vector quantity, when evaluating it we must keep track of direction.

## Average Speed Calculator Using Distance And Time

An online physics calculator which helps to calculate the average speed based on the given time and distance values. Speed, distance and time are always inter-related to each other. Speed and time are inversely proportional to each other. When speed increases, time decreases, and vice versa. For a varying velocity of an object, the average speed is the mean of the object in motion for a specific time period. Enter the distance and time values in the average speed calculator and click calculate.

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## Average Speed Vs Average Velocity

Speed and velocity might seem to be the same thing, but they’re not. Speed is a scalar quantity – it is defined by magnitude only. In simple terms, it tells you how fast an object is moving. On the other hand, velocity is a vector – it is defined not only by magnitude but also by direction. It tells you the rate at which an object changes its position.

Imagine you drove a car 100 meters forward and then 100 meters back. You would drive at a certain average speed in each direction, but you would have zero average velocity, as velocity is measured as the rate at which the position of the car changes, and, overall, the car didn’t change its position. Therefore, it is enough to say that the average speed of a car was 50 mph, but when calculating velocity we would have to add direction, let’s say 50 mph east.

And if you would like to know how fast your speed or velocity was changing you would need to calculate acceleration.

## Average Speed And Instantaneous Speed

Physics Narrative for 11-14

#### Calculations based on different measurements

As the interval over which an average speed is measured becomes shorter and shorter, so this speed becomes closer and closer to the instantaneous speed.

What you see on the speedometer of a car is the speed at that instant or moment the instantaneous speed. It’s the speed right now

. One way to find this instantaneous speed is to measure the rate of rotation of the wheels. Modern electronic devices allow accurate measurement of short time intervals and a sensor can measure the angle during these very short time intervals, effectively giving an instantaneous speed.

For the most part, however, we measure longer journeys: the distance travelled over longer time intervals from several seconds to minutes or even hours. The resulting calculation gives an average speed. We do not assume that the car maintained a constant speed during the time.

Average speed calculated at the end of a journey can tell you that:

- The athlete who completed the 800 metre race in 160 second had an average speed of 5 metre / second.
- The car that completed a 20 mile journey in 30 minutes had an average speed of 40 miles per hour.

###### Appears in theseCollections

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## The Average Speed Of An Object Tells You On An Average Rate At Which It Will Cover Distance That Is An Object Has A Speed Of 30km/hour Its Position Will Change On An Average By 30km Each Hour

**How to find average speed in physics**. How do i find the average speed of an object that traveled 3 miles in 2 hours? 36 s e c o n d s, which gives you 0.01666 as miles per second, which you can multiply times 3,600 to get an average speed of 60 m p h. D = distance, meters t = time,sec = short form for ‘the change’ d = short form for ‘the change in distance’

Average speed vs average velocity. Speed = distance time }= } }}}. Since average speed is the rate position changes, average speed = distance traveled/time taken.

A car travels along a straight road to the east for 100 meters in 4 seconds, then go the west for 50 meters in 1 second. Here are the differences in short. Suppose a sports car reaches a speed maximum speed of 250 km/h.

It tells us how fast or slow an object is moving. Average speed is an interesting concept in mathematics and physics. Whether you are test driving your brand new car, or just going for a quick jog or cycle, if you want to know how to find average speed, this calculator will come in handy.

Determine average speed and average velocity. Speed is the scalar quantity. John drove for 3 hours at a rate of 50 miles per hour and for 2 hours at 60 miles per hour.

Average speed = 16 m/s. However, its average speed during the trip comes out to be only 50 km/h. In these instances, other formulas exist for calculating the average speed.

Super Speed of light. Friends! From ancient times man

velocitytimegraphofparachutejumpweb (With images

## Scalar And Vector Quantities

Speed is a **scalar quantity**. It does not have a direction. It only has a size, meaning a magnitude or scale. Scalar quantities can go from 0 to infinitely fast.

A **vector quantity** has size and direction, as with the movement of an airplane in the sky. Velocity is a vector quantity.

Speed, being a scalar quantity, can never be less than 0 . Average and instantaneous speeds are always scalar quantities, which means you can always measure them with a number. Distance and time are also scalar quantities and can also be measured with numbers.

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## What Is Average Speed

Average speed of a particle is the ratio of Total distance covered by a particle to the Total time taken .

$ \large Average \ Speed = \frac $

A particle covers a distance by s = 10 m during a time interval t = 5 seconds.

Therefore $ \large \frac$ is the ratio of distance covered s and the time interval t . This ratio is termed as time rate of change of distance.

It is common known as Speed of the particle over that particular time interval t.

That is why this speed is known as Average Speed denoted mathematically as

$ u_ = \displaystyle \frac$

$ \displaystyle = \frac $

**Note :**If Speed is continuously changing with time then ,

$\Large v_ = \frac$

Solved Example: When a body covers first half distance with speed v1 and next half distance with speed v2 then find the average speed ?

Solution: Let the total distance = S

Total time taken , t = t1 + t2

$ \displaystyle t = \frac + \frac$

$ \displaystyle Average \ Speed = \frac $

$ \displaystyle Average \ Speed = \frac+ \frac }$

$ \displaystyle Average \ Speed = \frac $

## How Long Does It Take To Reach Terminal Velocity

It will take **the average human approximately 15 seconds** to reach 99% of terminal velocity with their belly facing the Earth. Reach 100% terminal velocity is very difficult, if not impossible, as acceleration drops exponentially as an object approaches its terminal velocity. This time will change if the personâs changes body position.

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## Using The Standard Speed Equation

**Find the distance that an object has traveled.**The basic equation that most people use to figure out how fast something is going is very easy to use. The first thing you’ll need to know is

*how far the object traveled*. In other words, how far is its starting point from its ending point?

**100 miles**away . In the next few steps, we’ll use this information to solve our equation.

**Find the time that the object took to travel that distance.**The next piece of information you’ll need is

*how long the object took as it traveled*. In other words, how long did it take to get from its starting point to its ending point?

**two hours**to make our journey.

**Divide the distance by the time to find the speed.**All you need are these two pieces of information to find your speed for the trip. The distance

*over*the time will give you the object’s speed.

**50 miles/hour**.

**Don’t forget your units.**Labelling your answer with the proper units is critical. Without units, it can be hard for other people to understand what your answer means. You may also lose points if you’re making this calculation for schoolwork.

**your distance units over your time units**. In our example, since we measured distance in miles and time in hours, our units are

**miles/hour**.

## What Is Instantaneous Speed

If the particle is not moving with uniform speed, the average speed completed in the above section depends on the time interval t and the instant when it was computed.

It becomes necessary to define a quantity, called **instantaneous speed** which does not depend on the time interval t .

We take the time interval t as it becomes very small and the corresponding distance travelled s .-

t 0

As t 0 , s 0

#### Note : Instantaneous speed is equal to the magnitude of instantaneous velocity.

The ratio of the infinitesimal distance covered and the corresponding infinitesimal time yields a finite value. This finite value is known as the instantaneous speed of the particle.

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## Difference Between Average Speed And Average Velocity

Average velocity involves only the displacement of the object. However, the magnitude of the displacement may be different from the actual path length. For this reason, to describe the rate of motion over a path, we use average speed.

Average speed is defined as the total path length travelled divided by the total time interval of the motion. Unlike average velocity, the average speed is a scalar quantity. Average speed does not tell us the direction of motion thus, it is always positive.

For better understanding, let us look at the example below:

**The average speed of the above car is 20 m/s, but the average velocity is 20 m/s, east.**

## Terminal Velocity Escape Velocity And Relativistic Velocity

Velocity is present in many aspects of physics, and we have created many calculators about it! The first velocity is the so-called terminal velocity, which is the highest velocity attainable by a free falling object. Terminal velocity occurs in fluids and depends on the fluid’s density. You can read more about it in our free fall with air resistance calculator.

Knowing how to calculate velocity is of particular importance in astrophysics since results have to be very accurate. If you’re interested in the world of massive celestial objects like suns or planets, visit our escape velocity calculator or orbital velocity calculator. You can learn a lot there!

In the high energy region, there is another important velocity – relativistic velocity. It results from the fact that no object with a non-zero mass can reach the speed of light. Why? When it approaches light speed, it’s kinetic energy becomes unattainable, very large or even infinite. You can check it with the relativistic kinetic energy calculator by filling the velocity field with the speed of light 299,792,458 m/s or 2.998e8 m/s in scientific notation. Moreover, this is a cause of other phenomena like relativistic velocity addition, time dilation, and length contraction. Also the Albert Einstein’s famous E = mc2 formula bases on the relativistic velocity concept.

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## What Is Uniform Speed

If the particle covers equal distances in equal intervals of time, it is said to be moving with uniform speed.

#### Student Notes:

# The slope of s-t graph at any time t gives the speed at that time t.

# The slope of x-t graph at any time t gives the instantaneous velocity

# For positive slope v is positive, for negative slope v is negative.

## What Are The Types Of Speed

Speed has many different types and terms to describe it:

**Speed**– how fast an object is travelling.**Velocity**– how fast an object is travelling in a certain direction.**Acceleration**– how quickly it takes an object to reach a certain speed.**Constant speed**– an object moving at the same rate.**Variable speed**– an object moving at a changing rate.**Average speed**– distance covered divided by time taken to traverse.**Instantaneous speed**– the speed at a particular instance.

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## How Fast Am I Going

Speed is not a precise term – there are a few more accurate meanings, and they should not be confused with each other. Let’s consider the differences between *instantaneous speed*, *average speed* and *rotational speed*. For the purpose of two first, we will try to visualize it with an example of driving a car.

You are driving along the long, open highway. You glance down at the speedometer of your car it reads 100 kilometers per hour. From this, you know how far you will drive if you keep the speed constant. We know that, in practice, keeping the speed exactly constant is almost impossible , and our speed fluctuates all the time, more or less. The actual distance you travel in an hour is the average of all these speeds. Conclusion – the ** average speed is the total distance traveled in a unit of time** .

So, what does the number your speedometer indicates really mean? That is your instantaneous speed your speed at this exact moment. According to the textbook definition, the ** instantaneous speed is the change in object position, x, between two times, tâ and tâ** .

## What Is The Unit For Speed

The **unit for speed is distance over time**, as it is defined as the amount of time it takes an object to cover a particular distance. The **base, or SI, unit is metres per second**, but this is not very practical in everyday life. You are likely more familiar with units such as **kilometres per hour, miles per hour and knots**. Any distance over time is a speed unit, so other units of speed include nanometres per fortnight, Boeing 787s per solar year, or bananas per Friedman.

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