속도 공식 (v = d/t): 무료 계산기, 단위 & 예제
Use v = d/t with clear unit conversions and home일 examples. 확인 every answer with a free 속도 calculator for distance, time, and 속력.
What 속도 Means
In introductory physics, 속도 is how fast an object’s position changes along a chosen direction. The 일horse 공식 for 평균 속도 is v = d / t, where d is 변위 (change in position) and t is the time interval. Travel 100 metres due east in 20 seconds and your 평균 속도 is 5 m/s east — direction included whenever the problem cares about it.
평균 속도 asks how much your position changed and how long that took. It ignores pauses and zigzags along the way. 순간 속도 is the same ratio over a tiny interval, but most home일 that gives a distance and a time wants the average.
If you already know distance and time and only need a 확인ed number, open the free 속도 calculator first, then come back to this guide for the unit traps and 일ed examples that usually cost marks.
변위 is the straight-line change from start to finish; path length is how far you actually travelled. “거리 travelled” without direction often means 속력. A change in position along a line means 변위. Use the 변위 calculator when you need that distinction before plugging into v = d / t.
속력 vs 속도
속력 is a scalar (magnitude only). 속도 is a vector (magnitude and direction). They match numerically on a straight path with no reversal, which is why early problems blur them. They split as soon as the path folds back.
Walk 4 km east then 4 km west in 2 hours. 평균 속력: 8 km / 2 h = 4 km/h. 평균 속도: 0 km / 2 h = 0. Same trip, different answers. Report 속력 when the mark scheme wants 속도 and you lose the direction mark even if the number looks right.
The 공식 and Rearrangements
Start from 평균 속도: v = d / t. Two rearrangements cover most questions:
Isolate the unknown, write values with 단위, then multiply or divide. When the question only gives 변위 and time — or asks for one of them from 평균 속도 — v = d / t is the equation you want.
With constant 가속도 and more than two of s, u, v, a, t in play, do not 힘 everything through 평균 속도. Use the kinematics calculator or the guide on how to choose the right kinematics equation to pick the SUVAT 공식 that matches the missing variable.
단위 Traps That Break 답s
Most wrong 속도 answers are unit 실수s. 변환 to a consistent set before you divide. School SI default is metres and seconds, so v comes out in m/s.
Minutes vs seconds
변환 minutes to seconds (× 60) unless every quantity is in minutes and the key expects per-minute 단위 — rare. Metres ÷ minutes gives m/min, not m/s. Markers usually want m/s.
km/h vs m/s
km/h → m/s: divide by 3.6 (or × 1000/3600). m/s → km/h: multiply by 3.6. Mixing kilometres with seconds without converting first produces a neat-looking number that is wrong by orders of magnitude.
일ed 예제 1: 120 m in 1 Minute
A runner covers 120 m due north in 1.0 minute. Find the 평균 속도 in m/s.
변환 time first: 1.0 min = 60 s. Then v = d / t = 120 m / 60 s = 2.0 m/s north.
Skip the conversion and 120 / 1 = 120 gives 120 m/min — a different quantity. In m/s the magnitude is 2. Include “north” when the problem states direction.
일ed 예제 2: 36 km in 1 Hour
A car travels 36 km due west in 1.0 hour on a straight road. Find the 평균 속도 (a) in km/h and (b) in m/s.
(a) Consistent km–h 단위: v = 36 km / 1.0 h = 36 km/h west.
(b) 변환 to SI, or convert the km/h result. 36 km = 36 000 m, 1.0 h = 3600 s, so v = 36 000 / 3600 = 10 m/s west. Same 확인: 36 ÷ 3.6 = 10 m/s west.
Both 36 km/h and 10 m/s are correct — same 속도, different 단위. Use the unit the question asks for.
흔한 실수
Sanity 확인: walking is about 1–2 m/s; highway 속력s are tens of m/s (~30 m/s ≈ 108 km/h). A “walking” answer of 50 m/s means your 단위 are wrong.
확인 Your 일 with 무료 계산기
Once the method is clear, verify the arithmetic. The 속도 calculator handles v = d / t problems and rearrangements so you can confirm the substituted 공식 and the number.
Master v = d / t with clean 단위 first. That habit carries forward: convert carefully, name what is missing, and state direction when the question asks for 속도 — not 속력.