What is Average velocity: Definition and 283 Discussions

The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of an object's speed and direction of motion (e.g. 60 km/h to the north). Velocity is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of bodies.
Velocity is a physical vector quantity; both magnitude and direction are needed to define it. The scalar absolute value (magnitude) of velocity is called speed, being a coherent derived unit whose quantity is measured in the SI (metric system) as metres per second (m/s or m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object has a changing velocity and is said to be undergoing an acceleration.

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  1. brotherbobby

    Average velocity for two different types of motion along same path

    Statement : Let me copy and paste the problem as it appears in the text. Attempt : I could solve (i) and (ii). Part of (iii) also. It is in the explaining bit where I am stuck, conceptually. I copy and paste my solutions using ##\text{Autodesk Sketchbook}^{\circledR}## hoping am not violating...
  2. brotherbobby

    Average velocity ##\bar{v}## for a uniformly accelerating particle

    Statement of the problem : Let me copy and paste the problem from the text. Please note it's part (i) that I am seeking to answer. I know the answer to part (ii). Solution : To show where my error appears, I take the time(s) to be ##t_f## and ##t_i##, whereby the given time interval ##t =...
  3. Spooky123

    Two Equations for Average Velocity?

    I know that average velocity is the change in position over the change in time. But im getting conflicting views from other sources saying thats its the total distance divided by the total time. For this question we would first find the respective vectors by multiplying the distance with the...
  4. C

    Average velocity of a particle

    For this, The solution to (a)(i) is 0 ft/s. However I got -4 ft/s. The formula I used was, ##v_{avg} = \frac{s_f - s_i}{t_f - t_i}## ##v_{avg} = \frac{\frac{1}{2}t^2_f - 6t_f + 23 - \frac{1}{2}t^2_i - 6t_i + 23}{t_f - t_i}## ##v_{avg} = \frac{ \frac{1}{2}(t^2_f - t^2_i) - 6(t_f - t_i)}{t_f -...
  5. MatinSAR

    Kinematics : Average velocity problem

    The car covers half of the road with an average velocity of v, so the elapsed time is equal to: ##t_1=\frac {d/2} {v}=\frac {d} {2v}## And it covers 1/4 of the road with an average velocity of 2v, so the elapsed time is equal to: ##t_2=\frac {d/4} {2v}=\frac {d} {8v}## Then it covers 1/8 of the...
  6. brotherbobby

    B In uniform acceleration, mean velocity ##\bar v = \frac{v_0+v}{2}##?

    Question : For uniformly accelerated motion ##a(t)=a_0\;\; \forall \text{times}\;t##, we can say that the average velocity for the entire motion ##\bar v = \frac{v_0+v}{2}##, where ##v(t)## is the final velocity at some time ##t## and ##v_0## is the initial velocity. How do we show that? Issue...
  7. agnimusayoti

    B Understanding Average Velocity in Linear Motion with Constant Acceleration

    I read Tipler's book: Physics for Scientists and Engineer and he derived the equation of motion for linear motion with constant acceleration algebraic. He stated that for linear motion with constant acceleration, the average velocity can be determined with mean value of initial and final...
  8. Stewkatt

    Motion of an Object: Displacement & Average Velocity

    An object starts from rest and accelerates at 3.0 m/s2 for 4.0 s. Its velocity remains constant for 7.0 s, and it finally comes to rest with uniform deceleration after another 5.0 s. Find the following: a. the displacement for each stage of the motion b. the average velocity over the whole time...
  9. O

    How to find d2 when given d1 and d, total time, and average velocity?

    I rearranged the displacement formula to d2 = d + d1. I used cosine law to solve for d2 since the triangle is not right-angled but I am not getting the correct answer or angle for d2. The angle I used in cosine law (based on the diagram) was 32+12+90 = 134. d = v(t) = 130(3) = 390 km/h [N 32 E]...
  10. aatari

    Find the Magnitude of Average velocity using the given vectors

    Hi Guys I've attempted the question but not sure if the approach I used is correct. Would someone please have a look at my solution and let me know if it makes sense. Thanks!
  11. mcastillo356

    Average speed (or maybe average velocity) of an athlete

    Hi PF It's a multiple choice exercise, and the answer is 10 m/s. I've been wondering why, but no way. Regards
  12. E

    Average velocity in a turbulent flow tube

    hi guys I'm really struggling to get the expression for average speed in turbulent flow The book explains absolutely nothing about how the integration is carried out, in addition to the fact that the logarithmic term becomes undefined when r = R what I did was carry out the integration up to...
  13. K

    Average speed and average velocity

    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...
  14. C

    How to find an average acceleration using an average velocity?

    I calculated the average velocity in a previous problem and got 1.146788991m/s over a time of 8.72s. I know I can’t use a_ave=(Vf-Vi)/(Tf-Ti) because I don’t know the final velocity and have no way to find it. Do I multiply average velocity by time?
  15. Alexandra Fabiello

    Finding distance east given west dist., velocities, and average velocity

    6.44 km * 1000 = 6440 m/2.51 m/s = 2565.737052 s = west time av = (6440 m + - east distance)/(2565.737052 s + east time) 2565.737052 s + east time = total time 1.28 m/s * total time = (6440 m) - (0.495 m/s * east time) 1.28 m/s * (2565.737052 s + east time) = (6440 m) - (0.495 m/s * east...
  16. D

    Instantaneous versus average velocity?

    I have a hard time understanding what this problem even means. So I can't even begin with it.
  17. karush

    MHB 2.6 Calculate the average velocity of the car in different time interval

    OK I just had time to post and hopefully ok but still typos maybe the graph was done in Deimos wanted to try tikx but not sure about the polynomial trying to as many physics homework before classes start on Aug 26 Mahalo
  18. Viona

    Average Velocity of gas molecules calculated with a Boltzmann distribution

    Hello What is the meaning of the average velocity of gas molecules calculated by Boltzmann distribution (in kinetic theory of gases)? Does all molecules have the same average velocity?
  19. K

    Can instantaneous velocity be different from average velocity?

    Homework Statement Is it possible for the instantaneous velocity of an object at some time, t1, to not be parallel to the average velocity over a short time interval, Δt=t2-t1? If it is not possible, explain why not. If it is possible, explain what this situation implies about the motion of...
  20. Mary27

    Runner's Average Velocity: 0.014 m/s

    Homework Statement A runner moves with a velocity of 4.0 m/s due east for 5.0 minutes. The runner then rests for 30 seconds, turns around and heads due west with a velocity of 5.0 m/s for 5 minutes. What is the runner's average velocity for the entire journey from start to finish? Homework...
  21. I

    How to get average velocity: Vaverage = V1 + V2 / 2?

    Homework Statement How to get Vaverage ( V ) = V1 + V2 / 2? Homework Equations How to get Vaverage ( V ) = V1 + V2 / 2? The Attempt at a Solution As I know Vaverage ( V ) = X2-X1 / t2-t1 = (delta)X / (delta) t
  22. I

    How to calculate the average velocity?

    Homework Statement The position of an object moving along the x-axis is given by x=a+bt^2, where a=8.5m,b=2.5 ms^-2, and t is measured in seconds. what is the average velocity between t=2.0 s and t= 4.0 s Homework Equations as we know, Vavg = xf-xi / tf-ti (f= final position and time and i=...
  23. steven george

    Average velocity of gas molecules in a container

    Homework Statement An ideal gas with molecules of mass m is contained in a cube with sides of area A. The pressure exerted by the gas on the top of the cube is P, and N molecules hit the top of the cube in a time Δt. What is the average vertical component of the velocity of the gas...
  24. Skrphys

    Power Equation: Instantaneous vs Average Velocity

    How does this version of the power equation relate to physical situations? Does the value you get give you an instantaneous power? Or is the velocity to be taken as the average velocity (an actual displacement over time)?
  25. M

    Not exactly a homework issue - just trying to find a formula

    Alright, first I should probably let you all know that this is very simple physics, so I'm just looking for a quick answer. 1. Homework Statement I'm trying to find a simple way to calculate the average velocity of an object where we know the average velocity during a number of segments of...
  26. Biscuit

    Average velocity when the interval has a domain

    Homework Statement If a ball is thrown into the air with a velocity of 40 ft/sec, its height (in feet) after t seconds is given by s(t) = 40t -16t^2. Find the average velocity, vAV (t), of the ball over the time interval (t, 2), for 0 < t < 2. Homework Equations change of x/change of...
  27. H

    Finding a second velocity with a first and average velocity

    Homework Statement A car travels along a straight line at a constant speed of 44.5 mi/h for a distance d and then another distance d in the same direction at another constant speed. The average velocity for the entire trip is 28.5 mi/h. NOTE: this is a practice problem. Homework Equations...
  28. H

    Basic physics question about average velocity

    Homework Statement a car starts from hither , goes 50km in a straight line to yon , immediately turns around, and turns to hither . the time for this round trip is 2 hours . the average speed of the car for this round trip is ? Homework Equations average velocity = disrance covered /time The...
  29. A

    Vectors: Displacement, average velocity & speed

    Homework Statement A plane flies 413 km east from city A to city B in 49.0 min and then 814 km south from city B to city C in 1.70 h. For the total trip, what are the (a) magnitude and (b) direction of the plane's displacement, the (c) magnitude and (d) direction of its average velocity, and...
  30. karush

    MHB 205.o6.03 Find the body's displacement and average velocity

    $\tiny{205.o6.03}$ $\textsf{A body on a coordinate line such that it has a position}\\$ $\textsf{$\displaystyle s=f(t)=\frac{16}{t^2}-\frac{4}{t}$ on the interval $\displaystyle 1\le t \le 4$ with $s$ in meters and $t$ in seconds }$ $\textsf{a. Find the body's displacement and average vellocity...
  31. C

    Average velocity vector of non-uniform circular motion?

    Homework Statement A particle starting from rest revolves with uniformly increasing speed in a clockwise circle in an xy plane. The center of the circle is at the origin of an xy coordinate system. At t=0, the particle is at x=0.0m, y=2.0m. At t=2.0s, it has made one-quarter of a revolution and...
  32. Iron_Man_123

    Average speed, average velocity for a road trip

    Homework Statement [/B] I'm very stuck at answering parts (c) and (d) Homework Equations speed = Distance/Time The Attempt at a Solution
  33. E

    What's the difference between velocity and average velocity

    Hello everyone, The velocity and average velocity it is the same? The formula of the velocity is: distance / time or [L] / [T]. The average velocity is it equal? thanks
  34. mihailo

    Average velocity of free particle

    Homework Statement The wave function is given as Ψ(x,t) = Ae^[i(k1x-ω1t)] + Ae^[i(k2x-ω2t)]. Show that particle average velocity Vav = ħ(k1+k2)/2m equals ω2-ω1/k2-k1. Average momentum of the particle is Pav = ħ(k2+k1)/2. Homework Equations p = ħk E=ħω K = 1/2 * mV^2 The Attempt at a Solution...
  35. C

    Calculating average velocity for this kind of motion

    Homework Statement For the first half of a straightly traveled path which is α=60° from some reference line, a body is moving with a velocity of v1=72 km/h. During the second half of a straightly traveled path, the body is moving with an angle of β=30° with a velocity of v2=36 km/h.What is the...
  36. Q

    How to calculate average velocity given distance and time?

    Homework Statement A motorist drives north for 35.9min at 73.3km/hr and then stops for 15.4min. He then continues north, traveling 114.5km in 1.93hr. What is his average velocity? Homework Equations avg velocity = xf - xi / time The Attempt at a Solution 35.9 min * (1 hr / 60 min) = 0.5983...
  37. R

    Average Velocity from Velocity Profile

    Hi I have velocity profiles at different lateral position of a channel. I want to calculate average velocity from velocity profile at those position. Can you suggest me any equation or literature? I attached here a sample datasheet also.
  38. W

    Finding average velocity in a velocity distribution

    Homework Statement A gas has a hypothetical speed distribution for N gas molecules with N(v) = Cv^2 for 0 < v < V0. Find (i) an expression for C in terms of N and v0 (ii) the average speed of the particles Homework Equations N/A The Attempt at a Solution (i) integrating N(v) with respect to v...
  39. jdawg

    Fluid Mechanics:Volumetric flow rate and average velocity

    Homework Statement . Air, at a flow rate of 30 [N/s], flows through the reducer shown below. In the 300 [mm] diameter section of the pipe the specific weight of the air is 9.8 [N/m3 ]. When flowing through the reducer the pressure and temperature will fall causing the air to expand and...
  40. B

    Average Velocity for Three People's Trips

    Person A travels 10.2m/s[forward]. Person B travels 10.4m/s[forward]. Person C travels 3.51m/s[forward]. Find the average velocity for the trio.I added all 3 velocities(just the magnitudes) and divided by 3, but my answer was different from the textbook's. I got 8.0m/s[forward], but the answer...
  41. B

    Average Velocity for One Person's Trip

    Homework Statement A person runs 10.0m[E] in 2.0s, then 5.0m[E] in 1.5s, and finally 30.0m[W] in 5.0s. Find the person's average velocity. Homework Equations Vav= total displacement/total time[/B] Total displacement=df=di The Attempt at a Solution [/B] I found the total displacement to be...
  42. I

    Average Velocity for a Runner Running Half a Lap

    Homework Statement A runner covers one lap of a circular track 40.0 min diameter in 62.6 s . Homework Equations If she covered the first half-lap in 28.7 s , what were her average velocity for that half-lap? The Attempt at a Solution Attempt 1: Initial Distance: 0 m Distance of a half-lap...
  43. tridianprime

    Simple Harmonic Motion Average Velocity

    Homework Statement At time t = 0, a point starts oscillating on the x - axis according to the law x = a sin(ωt). Find the average velocity vector projection (I assume it means magnitude based on previous questions in the book). Homework Equations The Attempt at a Solution I knew that the...
  44. CMATT

    Average velocity? Average speed?

    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 =...
  45. J

    Adding velocity vectors to get average velocity

    If you're driving in a car and map out all the displacement vectors, you can add the segments to get the total displacement. Correct? Why can't we add the various velocity vectors for the different segments to get the average velocity. ? Could you add up all the velocity vectors and divide by...
  46. D

    Calculate the average velocity of the car

    Homework Statement [/B] A car is stopped at a traffic light. It then travels along a straight road so that its distance from the light is given by x(t)=bt2−ct3, where b = 3.00 m/s2 and c = 0.130 m/s3 . Calculate the average velocity of the car for the time interval t= 0 to t= 10.0 s Homework...
  47. PhysicsBoyMan

    Tricky velocity/time problem without distance

    Homework Statement A person takes a trip, driving with a constant speed of 89.5 km/h, except for a 22-min rest stop. If the person's average speed is 77.8 km/h a) How much time is spent on the trip? b) How far does the person travel? Homework Equations v1 = 89.5 km/h -> t v2 = 0 km/h...
  48. Cosmophile

    Maximizing Average Velocity

    Homework Statement This is not a homework or coursework question for myself. A friend sent it to me and I'm simply looking for assistance in mathematically proving my answer to myself. Here is the question: "A cart rolls across a table two meters in length. Half of the length of the table is...