What is Average speed: Definition and 202 Discussions
In everyday use and in kinematics, the speed (commonly referred to as v) of an object is the magnitude of the rate of change of its position with time or the magnitude of the change of its position per unit of time; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero.
Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second (m/s), but the most common unit of speed in everyday usage is the kilometre per hour (km/h) or, in the US and the UK, miles per hour (mph). For air and marine travel the knot is commonly used.
The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in a vacuum c = 299792458 metres per second (approximately 1079000000 km/h or 671000000 mph). Matter cannot quite reach the speed of light, as this would require an infinite amount of energy. In relativity physics, the concept of rapidity replaces the classical idea of speed.
TL;DR Summary: A train on a level stretch of tracks, starting from a dead stop, steadily speeds up to 28 m/s in 2.0 minutes, and then slows to 18 m/s with a constant deceleration of 0.011 m/s^2. What is the average speed of the train for this whole thing (speeding up and slowing down)?
I know...
I drive car only at country roads allways at speeds 100-120km/h, no city and no idle time-heating engine etc.
Why computer allways show very low average speed , 40-48km/h?I allways have feeling that this speed is too low because I allways drive way faster then this. Indeed all my friends have...
I assumed since both pass the points they must have the same speed at both instances, so the average speed would be 15 and the speed when passing the object should be 30, since the equation of average speed.
Why we know that average speed of a single photon(in point particle view) equal the speed of EM wave?If average speed of a single photon smaller than c then there exist massive photons?
Though average speed over a finite interval of time is greater or equal to the magnitude of the average velocity, Instantaneous speed at an instant is equal to the magnitude of the instantaneous velocity at that instant. Why so?
Say that we have an instance where something falls down from a certain height with constant acceleration g. We know that the average speed with regards to the time period is less than (u+v)/2 since we spend less time at the higher speeds.
How do we actually calculate the average speed over a...
So thing that confusses me, is what is the difference regarding the calculation of speed and velocity? In think I should use the formula I wrote above to find the average velocity, but I don't understand what the formula for average speed will be then. By the way, when using the formula above...
Car A hits Car B's passenger side at intersection (T Bone). Car B flips over sideways in the direction of the driver's side. The intersection is basically level.
Car A is an Audi 5, roughly 3,900 lbs. Car B is a Lexus NX, roughly 4,000 lbs. Car B had recently stopped and was traveling...
Show that ##v_{av}=\frac{\hbar k_2 + \hbar k_1}{2m}## is equal to ##v_{av}=\frac{\omega_2 - \omega_1}{k_2-k_1}##. Which of the identities listed above (if any) would make the sign change between ##k_2## and ##k_1##?
One can attain a "wave packet" by superposing two or more sinusoidal waves...
My first most obvious attempt was to use the relation ##<\epsilon> = \frac{3}{5}\epsilon_F## and the formula for kinetic energy, but this doesn't give the right answer and I'm frankly not sure why that's the case. My other idea was to use the Fermi statistic ##f(\epsilon)## which in this case...
Homework Statement
Serway Physics Chapter 2
20. An object moves along the x-axis according to the equation ##x=3.00t^2 - 2.00t+3.00##,
where x is in meters and t is in seconds. Determine (a) the average speed between
t=2.00s and t=3.00s, (b) the instantaneous speed at t = 2.00s and at t=3.00s...
Homework Statement
In the file below.
Homework Equations
Speed= total distance over total time.
Acceleration = change of speed over time
The Attempt at a Solution
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I tought it is just E because of the first rule above. But then I doubt my answer since it moved with constant acceleration...
Homework Statement
I haven't taken a physics course yet, this is for independent study, so I don't have the strongest understanding quite yet. I was wondering if I could get some insight to this problem:
Susie has planned a trip to a city 60 miles away.
She wishes to have an average speed of...
Homework Statement
As we know the Average speed = Total distance / Total time but why in the case below
Distance traveled = s₁ + s₂ + s₃ and total time taken = s₁/v₁ + s₂/v₂ + s₃/v₃ How is it possible? so, altogether
Vav = s₁ + s₂ + s₃ / ( s₁/v₁ + s₂/v₂ + s₃/v₃)Homework EquationsThe Attempt...
Homework Statement
A motorcycle goes up a hill at a constant speed of 10 miles per hour and comes down at the speed of 25 miles per hour what is the average speed for the entire duration?
Homework Equations
Vavg =(vf-vi)÷2
The Attempt at a Solution
It seems very straightforward that this...
$\text{A person jogs eight complete laps around a $400 \, m$ track in a total time of $14.5 \, min$}. \\$
$\textit{a. Calculate the average speed in $km/h$}\\$
\begin{align*}\displaystyle \frac{(8)400 \, m}{14.5 \, min} \left(\frac{km}{1000m} \right) \left(\frac{60 \, min}{h}...
Homework Statement
Suppose that a heated gas comprised of electrons glows bright orange when it is in use. Estimate the average speed of the electrons in the gas. Model this gas as an ideal gas.
Homework Equations
None. I have no clue. This is a "review" question on a chapter titled "Current...
Homework Statement
If you walk to school at 4 mph and jog home at 6mph, what was your average speed?
Homework Equations
S = D/T
The Attempt at a Solution
Is the average speed not just (4 + 6)/2 = 5mph ?
If not, why not?
Homework Statement
The problem is as follows;
A boy begins to walk eastward along a street infront of his house and the graph of his displacement from the house is shown in the figure. His average speed for the whole time interval is equal to...
I found it somehow tricky to understand average speed and average power in mathematical fashion.
I suppose general idea of taking average of some quantity is: sum of all values/number of values.
how that idea fit's into idea of average speed=distance traveled/time traveled
similarly, average...
Homework Statement
In which conditions the average speed equals the Average of the Speeds?
Homework Equations
Average speed= (Xf-Xo)/(tf-to)
Average of the speeds= (vf+vo)/2
The Attempt at a Solution
I tried to set up a formula for vf and vo, but it would be false to determine that
vf=xf/tf...
Homework Statement
We're driving with a Uav of 80 km/h
The duration Δt is 2 h 45 min
On a rainy day, our Uav' is 65 km/h
If the distance is the same, how much more is the duration of the drive?
So, technically we want the result of Dt = Δt' - Δt
Homework Equations
Uav = Δx / Δt
The Attempt at...
The total distance traveled by trains is 18 km & the time spent is 20 minutes. Find the average speed of the train in kilometers per hour.
I' m stuck right in the beginning in converting 20 minutes to hours by dividing from 60 which I get this recurring decimal 0.33333
Homework Statement
So I have this homework exercise which I just can't seem to solve. It sound like this: "Half his time the cyclist was driving at the speed of 20km/h, half of the LEFTOVER way he drove at the speed of 16km/h. When his bike broke he finished his journey on foot at the speed of...
Its my first time ever being in Physics and I need help with this probably really simple problem.
It first says, a car is initially traveling at 25m/s and then coasts to a stop in 12 seconds. What is its acceleration? **I took 25/12 and got 2.08 m/s. Hopefully that part is right?
Then it asks...
Homework Statement
So here's a problem I need help with for my physics class that's due tomorrow night.
On a road trip, a driver achieved an average speed of 76 km/h for the first 86.0 km and an average speed of 38 km/h for the remaining 54.0 km. What was her average speed (in km/h) for the...
1. Homework Statement
Ok so for part ii) b)
I calculated the average speed as follow,
Average speed= 3792.6/ (2x266.67), where 3792.6m is the total distance, and 266.67s is the time when v=0 , i.e. the time from O to the turning point
But it should be 3792.6/ 400, where 400s is the time...
Homework Statement
A locomotive travels on a straight track at a constant speed of 40 mi/h, then reverses direction and returns to its starting point, traveling at a constant speed of 60 mi/h. What is the average speed for the round-trip?
Homework Equations
avgS = distance/time
t = d/40
The...
Hello,
I was wondering if someone out there could help me. The question:
The speed, v metres per second, of a particle is given as v=8sin2t+3cos2t
where t is in seconds.
i) Find the total distance traveled in the time interval 0≤t≤1
ii) Find the average speed over this time interval.
Homework Statement
A car is moving in a road and its average speed is 40 km/h. Then it moves back in that road by 60 km/h speed. What is the average speed of this car? ( The answer is not 50 km/h )
Homework Equations
Average speed= d/tThe Attempt at a Solution
I can't solve this. I get 50...
Homework Statement
A cow runs in a straight line, moving 108 m east in 16.4 seconds. It then turns and runs 93 m north in 7.64 seconds. a) What was the cow's average speed over the whole trip?
b) What was the cow's average velocity over the whole trip?
Homework Equations
average speed =...
Homework Statement
A golfer rides in a golf cart at an average speed of 3.1 m/s for 28s. She then gets out of the cart and starts walking at an average speed of 1.3 m/s. For how long must she walk if her average speed for the entire trip, riding and walking, is 1.8 m/s ?
Homework Equations...
Hello,
In the Kinetic-Molecular model for gas molecules in a container it is assumed that the square of the x-y-z velocity components is the same, how is it possible that we assume this?
Using the Maxwell-Boltzmann equation above, there is an example in my book (Giancoli 4th edition p. 481) where they use this to find the average velocity. I understand that it would just be the sum of all the speeds of the molecules divided by the number of molecules. But then I'm having...
Edit Background: The teacher doesn't teach we just do activities and have whole chapters worth of 20 mini assignments due every few days. Yes I did read the book found nothing.
1. Homework Statement
The average velocity of a car over a certain time interval is 35 mi/h. If the velocity of the...
New to physics, so I'm looking for guidance and help. Here is the following question:
A=19
B=0
On a road trip, a driver achieved an average speed of (48.0+A) km/h for the first 54.0 km and an average speed of (43.0-B) km/h for the remaining 86.0 km. What was her average speed (in km/h) for...
Homework Statement
You drive on Interstate 10 from San Antonio to Houston, half the time at 58 km/h and the other half at 103 km/h. On the way back you travel half the distance at 58 km/h and the other half at 103 km/h. What is your average speed (a) from San Antonio to Houston, (b) from...
1. a man drives from a to b with car and speed of 20 km/h and returns from b to a immediately with speed of 30 km/h. what's the average speed and average velocity?
2. V=at+Vi etc
3. I think avg. speed will be 25 km/h and avg. velocity is -10 km/h.
Is that right?
thanks :)
Homework Statement
On a straight road you start your car and increase the speed at a steady rate to 45 miles per hour during a 5 second interval. Calculate:
a)the average speed during the 5 seconds
b) the acceleration in miles per second at t = 3.2 sec. after you start your car
c) the speed of...
1. I'm a middle school science teacher without a science or math background. My goal here is to avoid teaching an explanation that kids will have to unlearn later in their academic career. I'm designing a lesson to teach students how to answer this question:
2. Limitation: students are NOT...
"A car accelerates from rest over 400 metres in 19 seconds. The driver then brakes and the car stops in 5.1 seconds with constant deceleration."
Part one of the question is "calculate the acceleration for the first 400m" which went just fine:
x=ut+(1/2)at^2
400=180.5a
a=2.22 m/s
Now the...
Homework Statement
What is the ratio of the average speed of an atom of neon to another atom of neon at twice the temperature?
(A) 1:1
(B) 1:1.4
(C) 1:2
(D) 1:4
Homework Equations
KE = 3/2RT
The Attempt at a Solution
I used the above equation and substituted 2 for T for twice the temperature...
Ok let me just type the question and get to the real question I have.
If you traveled one mile at a speed of 100 miles per hour and another mile at a speed of 1 mile per hour, your average speed would not be (100 mph+ 1 mph)/2 or 50.5 mph. What would be your average speed? (Hint:what is the...
It is my understanding that while instantaneous speed is the magnitude of instantaneous velocity, average speed is , in general, not the magnitude of average velocity, since average speed is total distance traveled divided by change in time. Why is the mathematical definition of average speed as...
Homework Statement
An object starts at the origin, position A; then travels 20 m to position B; then returns to position A. From A to B the average speed is 10 m/s; on its way back the average speed is 6 m/s. What is the average speed for the entire trip?
Homework Equations
average speed =...
Homework Statement
A truck covers 40.0m in 7.15 s while uniformly slowing down to a final velocity of 3.50 m/s. a.) Find the truck's original speed b.) Find it's acceleration
Homework Equations
Δx = Vav(Δt) = (V+Vo/2)Δt
a=(V-Vo)/(Δt)
The Attempt at a Solution
Part A.)...