# What is initial speed: Definition and 135 Discussions

Initial D (Japanese: 頭文字イニシャル D, Hepburn: Inisharu Dī) is a Japanese street racing manga series written and illustrated by Shuichi Shigeno. It was serialized in Kodansha's seinen manga magazine Weekly Young Magazine from 1995 to 2013, with the chapters collected into 48 tankōbon volumes. The story focuses on the world of illegal Japanese street racing, where all the action is concentrated in the mountain passes and rarely in cities or urban areas, and with the drifting racing style emphasized in particular. Professional race car driver and pioneer of drifting Keiichi Tsuchiya helped with editorial supervision. The story is centered on the prefecture of Gunma, more specifically on several mountains in the Kantō region and in their surrounding cities and towns. Although some of the names of the locations the characters race in have been fictionalized, all of the locations in the series are based on actual locations in Japan.
Initial D has been adapted into several anime television and original video animations series by OB Studio Comet, Studio Gallop, Pastel, A.C.G.T and SynergySP. A live action film by Avex and Media Asia was released in 2005. Both the manga and anime series were initially licensed for English-language distribution in North America by Tokyopop (2002–2009). However, the anime license has since been picked up by Funimation (now Crunchyroll), while the manga was relicensed by Kodansha USA in 2019.
As of April 2021, Initial D had over 55 million copies in circulation, making it one of the best-selling manga series in history.

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1. ### Solved problem: Projectile in slanting tunnel

(a) Find the initial speed. Solution The relevant equations are (4) and (5) derived here and reproduced below as (1) and (2) respectively: \begin{align} & \frac{\Delta x}{\tan\!\theta-\tan\!\varphi}=\frac{2v_{0x}^2}{g} \\ & \tan\!\varphi=\frac{1}{2}(\tan\!\theta+\tan\!\omega)...
2. ### Initial speed of an object launched from Mars

U1 = -GMm/r K1 = (1/2)mvi^2 U2 = as r approaches infinity, U2 approaches zero K2 = (1/2)mvf^2 (1/2)mvi^2 - GMm/r = (1/2)mvf^2 + 0 vi = √(vf^2 + (2GMm)/r) = √(250,000 + 2(6.7 E-11)(6 E23)/3400) = 153776.815 But that is not the correct answer, can anybody see my mistake/misunderstanding?
3. ### Why we jump with the same initial speed on 2 different planets?

In every single question asking about the maximum height you get from jumping in 2 different planets they consider that the speed you leave the ground is constant. Why is that? Speed would be constant if impulse were constant. Impulse would be constant if both force and time were constants...
4. ### Minimum initial speed to spin a particle around a disk (with gravity)

For this problem, since the weight force on the "particle" (child) is not always aligned with the tangential circular path of the disks, I couldn't think of a way to use rotational kinematics equations. As such, I tried to solve the problem using work principles (namely, that the change in...
5. ### Space elevator minimum initial speed

Homework Statement In the far future, humans have built a space elevator as a cheap means of access to space. However before that could be done, a few basic principles had to be worked out. . . a) What is the minimum initial speed (in an Earth-centered inertial reference frame) needed for an...
6. ### Initial speed of the proton?

Homework Statement The moving proton hits the second proton, which we consider to be stationary. In the moment of central strike gap between the protons is 10(-13)m. What was the initial speed of the moving proton? Proton mass is 1.67*10(-27)kg and charge 1.6*10(-19) C. Homework Equations...
7. ### Find the initial speed of a block before it hits a spring

Homework Statement Homework Equations W =ΔKE The Attempt at a Solution found work done by spring -1.3 =ΔKE -1.3 = KEFINAL - KEINITIAL -1.3 = .5(0.25)(VFINAL2) - .5(0.25)(VINITIAL2) Since v final is 0 since it stops momenteraly at the bottom of the spring -1.3 = - .5(0.25)(VINITIAL2)...
8. M

### Initial Speed of Hanging Mass (HW Check)

Homework Statement A mass hangs from a light string of length 45cm attached at its other end to the ceiling. If the mass is given an initial speed of 5m/s, what is its speed when it reaches point A in its circular path (see Figure 1)? https://imgur.com/a/ERdlD Homework Equations ##E_i = E_f##...
9. ### Block projected up inlcline with initial speed

Homework Statement I have a block on an inclined plane (the angle is 40). The block is projected with an initial speed of 2m/s and μ=0.05. I need to find the time it takes the block to go up the inclined plane and return to the point it started out. Homework EquationsThe Attempt at a Solution...
10. ### Postion vs time graph without time or initial speed?

Homework Statement Consider the system shown to the right. Particles 1 and 2 are fixed in place while particle three is placed at the location shown and released. Let’s look at the mechanics of q3, which has a mass of 3.00 X 10-5 kg. What will be the net force on q3?What will be q3’s...
11. ### Momentum problem: 2 carts, finding initial speed

Homework Statement A 2.0-kg cart collides with a 1.0-kg cart that is initially at rest on a low-friction track. After the collision, the 1.0-kg cart moves to the right at0.50 m/s and the 2.0-kg cart moves to the right at0.30 m/s .If the positive direction is to the right, what was the initial...
12. ### What's the minimum initial speed to score

Homework Statement Alex Morgan is going to kick a soccer ball into the Canadians goal during the 2015 world cup. Alex kicks the ball straight at the goal from 20.0 m away, and it launches off the ground at an 33.3 degree angle. Assume the goalie is busy faking an injury and ignore air...
13. ### Possible to solve for the initial speed of a projectile?

Is it possible to solve for the initial speed of projectile hitting a target given that we know the direction (vector) that it is released at and the point on a the surface that it is hitting? If so how would you go about finding an equation to solve for this? I realize that this is a...
14. ### Calculate initial speed of an athlete - projectile motion

Homework Statement An athlete can cover 3.0 m for a standing long jump. Assuming that this athlete jumps at an angle of 45 degrees to the horizontal. calculate the speed at which the jumper can launch herself from a standing start. Assume g =10 ms^-2 and no air resistance Assume that horizontal...
15. ### Does initial speed of a gun affect bullet velocity?

My brother and I were having an argument so I decided to make an account on this forum. Say you were to lurch you hand forward while firing a pistol. Would that affect the max velocity of the bullet?
16. ### How to chose the angle and initial speed to hit two objects

1. The prIoblem statement, all variables and given/known data You are the chief of the Angry Birds (Google it, if you don’t know the reference...it’s not important). You can shoot red birds from a catapult, and they will fly as projectiles under the effect of gravity. Gravity points downwards...
17. ### Projectile motion, finding initial speed

An object fired at an angle of 30° above the horizontal takes 2.5 s to travel the last 12 m of its vertical distance and the last 10 m of its horizontal distance. With what speed was the object launched? (Note: This problem does not stipulate that the initial and final elevation of the object...
18. ### Find the car's initial speed

Homework Statement A 5000-kg freight car rolls along rails with negligible friction. The car is brought to rest by a combination of two coiled springs as illustrated in the figure below. Both springs are described by Hooke's law and have spring constants with k1 = 1700 N/m and k2 = 3000 N/m...
19. ### Motion between two charged surfaces, find initial speed

Homework Statement Two charged, parallel, flat conducting surfaces are spaced d = 1.3 cm apart and produce a potential difference ΔV = 625 V between them. An electron is projected from one surface directly toward the second. What is the initial speed of the electron if its comes to rest just at...
20. ### Finding Initial Speed given Kinetic Friction, Mass, and more

Hi, I'm new here and I'm having trouble with a question. 1. Homework Statement A 20.0-kg curling stone is released at the hog line and moves 28.35 m [W] to sit on the button and score a point. If the coefficient of kinetic friction between the stone and the ice is 0.00200, what was the...
21. ### Is there a difference between initial speed and initial velocity?

If a projectile is thrown at an angle of 60o and it's initial speed is 30m/s, find the maximum height, time used for the ball to reach the ground, the horizontal range the ball reached from starting point, and the final velocity. So can i use 30m/s as the initial velocity?
22. ### Calculating force from distance traveled and initial speed of projectile

Homework Statement Estimate the average force exerted by a shot-putter on a 7.0-kg shot if the shot is moved through a distance of 3.0m and is released with a speed of 10m/s . Homework Equations F=ma Maybe the Five Equations for constant acceleration? The Attempt at a Solution So my guess is...
23. ### Finding Initial Speed Given Range

Homework Statement If you want to use a catapult to throw rocks, and the max range is 0.67 km, what initial speed must the rocks have as they leave the catapult?Homework Equations v=Δr/Δt The Attempt at a Solution I sketched a graph of the projectile trajectory with the desired range on the...
24. ### Finding the initial speed of two balls.

Homework Statement Ball A is thrown straight upward and returns to its original level in 2 seconds. Ball B is thrown at a 40 degree angle above the horizontal and also returns to its original level in 2 seconds. What is the initial speed of each ball. Homework Equations ΔV=at...
25. ### Calculating the initial speed of an object that decelerates in a ramp.

Homework Statement Hello, An object moves at constant speed in a horizontal surface. Suddenly, a ramp comes along its way. The object starts to climb such ramp. Due to this, the object starts to lose speed. At certain distance, the object loses all of its speed. I want to calculate the value...
26. ### Calculating Initial Speed of a Meteorite Based on Energy Transformations

It's not homework training problems...I have the answers but I get wrong ans. Homework Statement problem 1 What was the initial speed of a meteorite of mass 1 kg if a total of 18 MJ of thermal and other forms of energy were produced during its fall through the atmosphere of a planet and its...
27. ### How Does Physics Apply in the New Olympic Sled and Spring Event?

In a new Olympic event athletes run as fast as they can, jump onto a sled, ride it down a hill and compress a spring as far as they possibly can. (who thinks of these any ways) a. Consider a 55.0 kg athlete that makes it to a top speed of 12.5 m/s before jumping onto a 15.0 kg sled. What is...
28. ### Stone throw find initial speed

Homework Statement a stone is thrown vertically downward from the top of 40 m tall building with an initial speed of 1 after 2s the stone will have traveled a distance of? Homework Equations x=vt+0.5at^2 vf=vi+at The Attempt at a Solution 1(2)+0.5(-9.8)(2)^2=-17.6 the answer i...
29. ### Calculate Initial Speed of Ball Thrown Vertically 14m in 3s

Homework Statement A ball thrown vertically from ground level is caught 3.0 s later by a person on a balcony which is 14 m above the ground. Determine the initial speed of the ball. t = 3.0 s, d = 14 m, Vi = ? Homework Equations d = Vi.t + 1/2 a.t^2 The Attempt at a Solution I...
30. ### Why Is the Initial Speed of a Ball Thrown Vertically 19 m/s?

A ball thrown vertically from ground level is caught 3.0 s later by a person on a balcony who is 14 m above the ground, determine the initial speed of the ball. When I first tried doing this problem, I tried using the speed equation of distance/change in time, so I divided 14 by 3 which gave...
31. ### Find the initial speed of jump using range and max height

Homework Statement A dog jumps a distance, L, and a maximum height, H, where the dog only has horizontal velocity when it travels through the hoop. What is the speed of your dog when he leaves the ground? What is the speed of your dog when he goes through the loop? Both answers should NOT...
32. ### Simple Projectile Motion Problem. Unknown initial speed.

A ball is thrown at an unknown speed at an angle of 30 degrees. The initial and final height from the ground is 0 meters. What speed should the ball be launched at in order for it to land on the ground 3 meters from the launch point? Here is what I tried...
33. ### Initial Speed and Projectile Motion

Homework Statement So it's a projectile motion problem. I draw a graph showing the parabolic trajectory of the ball, with the start point at the origin. It's final x = 24.8m and final y = 0m Homework Equations We have three constant acceleration equations we use in my course: \vec{v}_{fx}...
34. ### Accelerated Motion in [2]- initial speed and launch angle

Homework Statement The range of a projectile is 483m, and it reached a maximum height of 65m. What were the initial speed and launch angle of the projectile? Assume the start and finish heights are equal. Homework Equations The Attempt at a Solution I just need a push in the...
35. ### What is the speed of the ball when it leaves Sarah's hand?

Homework Statement The question I am struggling with is the second version of a similar problem so to make it easier for me to receive assistance, I'll post both parts: Julie throws a ball to her friend Sarah. The ball leaves Julie's hand a distance 1.5 meters above the ground with an...
36. ### Find the Initial Speed given Distance Traveled and Time Taken

I performed a lab where we needed to find the mathematical relationship between the starting speed (initial velocity) and the stopping distance. However, I'm pretty sure we recorded all the initial speeds incorrectly. Is there a way to calculate the initial speed knowing the Distance Traveled...
37. ### Initial speed with Angle and distance

I have been working this one all day. No luck as far. The question: A projectile is launched at an angle of 53.1° with respect to the horizontal, as shown in Figure 2-34. ( Ill try to give you a picture of example 2-34) It strikes a target that is 120m away horizontally and 160m below the...
38. ### Initial speed of proton between parallel plate=?

Homework Statement So I just wrote my midterm in physics, and I was curious on how to do the last question. Parallel plates, length 5.5cm, Distance between them is 0.3 cm Electric Field (E) is 5.4x10^4 Asking what is the initial speed of a proton going through the parallel plates if it just...
39. ### Two balls are thrown vertically upward, one with an initial speed twic

Homework Statement Two balls are thrown vertically upward, one with an initial speed twice that of the other. The ball with the greater initial speed will reach a height - twice that of the other - 4 times that of the other Homework Equations dy = vt + 1/2 at^2 [if i use this equation, i...
40. ### Find friction from stopping distance and initial speed.

According to test performed by the manufactures, an automobile with an initial speed of 75 km/h has a stopping distance of 25 m on a level road. assuming that no skidding occurs during breaking, what is the value of μ , between the wheels and the road required to achieve the stopping distance...
41. ### Coulombs law, initial speed to collide with other nucleus

Homework Statement A helium nucleus has radius rHe = 1.9 fm, mass m = 6.6 × 10-27 kg, and charge +2e. A gold nucleus has charge +87e and radius rAu = 7.0 fm. What initial speed must a helium nucleus have if it is to come into contact with a fixed gold nucleus in a head on collision...
42. ### Maximum Initial Speed of an Overdamped Oscillator

Homework Statement An overdamped oscillator with natural frequency w and damping coefficient y starts out at a position xo>0. What is the maximum initial speed (directed toward the origin) it can have and not cross the origin? Homework Equations Overdamped Case Equation...
43. ### Freefall Arrow Problem: Finding the initial speed and maximum height

1. An arrow is shot vertically upward with an initial speed of 25 m/s. When it's exactly halfway to the top of its flight, a second arrow is launched vertically upward from the same spot. The second arrow reaches the first arrow just as the first arrow reaches its highest point. What is the...
44. ### Free Falling Objects in GR: Initial Speed Matters

In GR a object follows a geodesic when free falling as I understand. A object near the sun for instance wil fall to the sun following that line. If the initial speed is different the path will be different. How can it be that the geadesic is depending on the initial speed of the object...
45. ### The initial speed of two moving bodies given an increment of velocity.

Car A has twice the mass of Car B but only half as much Ek (Kinetic Energy). When both cars increase their speed by 6.00m/s their resulting Ek's are equal What were the initial speeds of both cars? ANS 1= 4.24m/s ANS 2= 2.12 m/sKe=1/2mV^2 m(a)=2m(b) Ek(a)=1/2Ek(b)...
46. ### Calculating Ball's Initial Speed: All Gravitational Energy

Acceleration -- all the energy is gravitational what speed was the ball thrown at? Homework Statement A ball is thrown up in the air and reaches a height of 2.2m assuming that all the energy is gravitational what speed was the ball thrown at. Homework Equations I cannot find the...
47. ### How can i get an initial speed without acceleration or time?

How can i get an initial speed without acceleration or time?? Homework Statement Hi..heres the problem: A 4WD traveling East has collided with a stationary car, the 4WD's skid marks are 15m long until the point of collision. The 4WD is sent 35degs South for 15.8m and the car is sent...
48. ### How to find initial speed of something without time or acceleration

Homework Statement Hi..heres the problem: A 4WD traveling East has collided with a stationary car, the 4WD's skid marks are 15m long until the point of collision. The 4WD is sent 35degs South for 15.8m and the car is sent 55degs North for 15m. The car has a mass of 1150kg and the 4WD's is...
49. ### Calculating Initial Speed of a Projectile Using Gravity, Height, and Range

Homework Statement Find the initial speed (Vo) in Projectile motion in terms of Gravity (g) Height (H) Range (R) Homework Equations Nothing has been given, however, have found these so far... Initial Velocity = sqrt((1/2 * g * R^2)/(cos2θ * (R * tanθ + H)) And a few others which are...
50. ### Weight of the support of a pendulum with initial speed

Hi, I'm interresting about the weight of the support of the pendulum with an initial speed. It is the http://en.wikipedia.org/wiki/Pendulum but with an initial speed. The mass come at top with straight initial speed and after turn around the pendulum. I attempt to have the weight of the...