An Exercise In Safety
Divide into groups of \ and perform the following investigation. Each group will be performing the same investigation, but the aim for each group will be different.
Choose an aim for your investigation from the following list and formulate a hypothesis:
Do cars travel at the correct speed limit?
Is is safe to cross the road outside of a pedestrian crossing?
Does the colour of your car determine the speed you are travelling at?
Any other relevant question that you would like to investigate.
On a road that you often cross, measure out \ \ along a straight section, far away from traffic lights or intersections.
Use a stopwatch to record the time each of \ cars take to travel the \ \ section you measured.
Design a table to represent your results. Use the results to answer the question posed in the aim of the investigation. You might need to do some more measurements for your investigation. Plan in your group what else needs to be done.
Complete any additional measurements and write up your investigation under the following headings:
Aim and Hypothesis
Answer the following questions:
How many cars took less than \ \ to travel \ \?
What was the shortest time a car took to travel \ \?
What was the average time taken by the \ cars?
What was the average speed of the \ cars?
Convert the average speed to \.
Whats The Difference Between Mph And Kph
Kilometers per hour has an abbreviation of kph and it refers to the number of kilometers a given object traveled in one hour. Conversely, miles per hour has an abbreviation of mph and it refers to the number of miles a given object traveled in one hour. Both are units of measurements used for speed.
If you want to convert an mph value to a kph value, take the mph value and multiply this by 1.61. On the contrary, if you want to convert a kph value to an mph value, take the kph value and multiply this by 0.61. This is because:
1 mile = 1.61 kilometers, and 1 kilometer = 0.061 miles
You can breakdown both mph and kph into meters per second and feet per second. For kph, all you have to do is multiply the total speed by 1,000 then divide the value you get by 3,600. For mph, all you have to do is multiply the total speed by 5,280 then divide the value you get by 3,600.
The main difference between these two units of measurement is one is from the metric system while the other is from the US customary system.
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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More Examples On Average Speed
1. Rahul runs 4 miles from his house to the playground in 2 hours every day. What is his average speed?
Ans: Average Speed = total distance ÷ total time
Average Speed = 4 miles ÷ 2 hours
Average Speed = 2 miles per hour
2. Anitya walks from A to B, covering 8 miles of distance, for 2 hours. What is the average speed?
Ans: Average Speed = total distance ÷ total time
Average Speed = 8 miles ÷ 2 hours
Average Speed = 4 miles per hour
Another formula is used when the speed during the journey changes. If an object covers some part of the journey with one speed and changes the speed to cover the other part of the journey, this formula is applied. Let us learn from an example.
3. An aeroplane travels from the United States to Malaysia, a distance of 9000 miles, in 18 hours and travels from Malaysia to India, a distance of 3000 miles in 5 hours.
Ans: To find the average speed of the locomotive, you will have to do the following formula.
Distance travelled = 9000 miles + 3000 miles
Distance travelled = 12000 miles
Time taken = 18 hours + 5 hours
Time taken = 23 hours
Is Velocity The Same As Speed
Velocity and speed are very nearly the same – in fact the only difference between the two is that velocity is speed with direction. Speed is what is known as a scalar quantity, meaning that it can be described by a single number . It is also the magnitude of velocity. Velocity, a vector quality, must have both the magnitude and direction specified, e.g. travelling 90 mph south east.
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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.
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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What Is Speed And Average Speed
What is average speed? Average speed is calculated by dividing the total distance that something has traveled by the total amount of time it took it to travel that distance. Speed is how fast something is going at a particular moment. Average speed measures the average rate of speed over the extent of a trip.
How To Calculate The Average Speed Of A Car
Let us say that you travelled a certain distance with your car and want to calculate its average speed. The easiest way to do that would be by using the speed calculator above, but if you prefer, you can also do the math yourself. Either way, one needs to know the distance. If you have noted the distance on your odometer then you can use that number. Other options are to use a map and measure the distance travelled based on your actual path , or to use a GPS reading if you used navigation during the whole trip. Then you need to know the travel time. Make sure to subtract any rests or stops made from the total trip duration.
For example, if the total distance travelled was 250 miles and the time it took was 5 hours, then the average speed was 250 / 5 = 50 miles per hour . If the distance was 200 kilometers and it took 4 hours to cover it, then the speed was 200 / 4 = 50 km/h .
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How To Calculate Average Speed
To calculate the average speed of an object, you must know the total distance an object travels and the total elapsed time of its whole journey.
The distance/speed/time triangle is handy for calculating this and two other scalar quantities :
The three parts in the triangle are set up in their correct positions mathematically:
Average speed is especially useful because it takes into account the reality of an event, rather than assuming something or someone is moving at a constant speed.
The porpoise could have started slowly, sped up, paused to play, and continued. That three-toed sloth may have stopped for a moment to catch its breath before hurrying onward. You might have to make numerous stops when walking a dog, but in all three cases, you can easily calculate average speed by dividing the total distance traveled by total elapsed time.
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.
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Speed Distance & Time Calculation
In order to use the above speed, distance & time calculator, or do such math on your own, you will need to know two out of three metrics: speed, distance, time. You will need to convert the metrics to the same time and distance units, e.g. miles, kilometers, meters, yards, feet, and hours, minutes or seconds. For example, if you have speed in mph , time should also be in hours. If you have distance in kilometers, then speed should also be in km/h .
The unit of the result will depend on the units you input, but our speed calculator will conveniently display additional units where appropriate.
How To Use The Speed Calculator
Use this speed calculator to find out the value of speed without having to perform manual calculations with the speed formula. Its also known as an average speed calculator, mph calculator, and a time distance calculator. Its a very simple online tool which provides instant results. Here are the steps to follow for this calculator:
- First, input the value of the Distance and choose the unit of measurement from the drop-down menu.
- Then input the value of the time, make sure to be as specific as possible. Also, choose the unit of measurement from the drop-down menu.
- After entering all of the required values, the speed calculator performs the calculation for you to give you the value of Speed.
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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 .
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.
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.
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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 the 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 the same as the direction in which the object is moving
Distinguish Between 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 is the total distance travelled by an object to the total time taken. However, average velocity is the change in position or displacement divided by the time intervals in which the displacement occurs.
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Problems Related To Both Average Speed And Average Velocity
1. A car travels along a straight road to the east for 120 meters in 5 seconds, then goes west for 60 meters in 1 second. Determine average speed and average velocity.
Solution:
Distance = 120 meters + 60 meters = 180 meters
Displacement = 120 meters 60 meters = 60 meters, to east.
Time elapsed = 5 seconds + 1 second = 6 seconds.
Average speed = Distance / time elapsed = 180 meters / 6 seconds = 30 meters/second.
Average velocity = Displacement / time elapsed = 60 meters / 6 seconds = 10 meters/second.
2. A runner is running around a rectangle track with length = 50 meters and width = 20 meters. He travels around the rectangle track twice, finally running back to the starting point. If the total time he takes to run around the track is 100 seconds, determine average speed and average velocity.
Solution:
The circumference of the rectangle, which is the distance travelled in one round = 2 + 2 = 100 meters + 40 meters = 140 meters.
When a runner runs around the rectangle twice = 2 = 280 meters.
Distance = 280 meter
When Is The Average Velocity Zero
For instance, if a remote-controlled car is racing from Point A to Point B and back to Point A, there is no overall car displacement. In that case, the speed of the car can be measured but not its velocity. If the same car moves from Point A to Point B and stays there, there is definite displacement in a certain direction. It can be measured in such cases. In simpler words, average velocity is just the average speed with a direction. If a trip starts and ends at the same point, the total displacement is zero, so the average velocity is zero.
Here is a video that provides a detailed explanation of average speed and average velocity with animations!
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