위치 에너지 공식 (PE = mgh): 무료 계산기 & 예제
계산 방법 potential 에너지 with PE = mgh (the mgh 공식). 풀이 예제s plus a free potential 에너지 calculator for 질량, height, and joules.
계산 방법 위치 에너지 (Quick 답)
Near Earth’s surface, gravitational potential 에너지 is PE = m g h (the mgh 공식). Multiply 질량 in kilograms by g (usually 9.8 m/s²) by height in metres above your chosen zero. The answer is in joules (J).
Need a 확인ed number now? Open the free potential 에너지 calculator (PE = mgh) — then come back for reference-level traps and 일ed examples.
What Is the mgh 공식?
mgh means 질량 × gravitational field strength × height. It estimates gravitational potential 에너지 (PE or Ug) in the near-surface model used in most school problems. The 공식 does not care how the object got there — only how high it is relative to a chosen PE = 0 level.
Lift a book onto a shelf and you do 일 against gravity; that 일 shows up as extra PE. Drop the book and stored PE converts into kinetic 에너지 as it falls.
PE = mgh Rearrangements
Verify any rearrangement in the free PE calculator.
Choosing g: 9.8, 9.81, or 10
Use the value printed on the exam paper. Many courses accept g = 9.8 m/s² or g = 10 m/s² for estimates. Engineering-style problems often want 9.81. Mixing 9.8 in 일ing and 10 in a “확인” will make your answer look wrong even when the method is fine.
키 and the Reference Point
키 h is measured from whatever level you call PE = 0. Floor, table, ground, or the bottom of a ramp can all be valid zeros if you stay consistent. Changing the zero shifts every PE value by the same amount; 에너지 differences between two heights stay the same.
If a ball rises from 1.0 m to 3.0 m above the floor, the change in PE uses Δh = 2.0 m, not the absolute heights alone.
단위 Traps That Break 답s
질량 in grams
변환 grams to kilograms before multiplying (÷ 1000). Using 500 g as if it were 500 kg inflates PE by a factor of 1000.
키 in centimetres
변환 centimetres to metres (÷ 100) for SI joules. 80 cm is 0.80 m.
무게 vs 질량
무게 is already a 힘 (W = mg). Do not multiply 무게 by g again. If the problem gives 무게 in newtons, PE = W × h (same as mgh).
풀이 예제
예제 1: how to 계산 PE for 2.0 kg lifted 1.5 m
Take g = 9.8 m/s² and the floor as PE = 0. PE = m g h = (2.0)(9.8)(1.5) = 29.4 J. Rough 확인 with g = 10: about 30 J.
예제 2: mgh 공식 — find height from 25 J
A 0.50 kg ball stores 25 J relative to the ground. With g = 10 m/s², h = PE / (m g) = 25 / (0.50 × 10) = 5.0 m. With g = 9.8, h ≈ 5.1 m.
예제 3: pe = mgh with height in cm
m = 1.2 kg, h = 80 cm = 0.80 m, g = 9.8. PE = (1.2)(9.8)(0.80) = 9.408 J ≈ 9.41 J. Leaving h as 80 would wrongly give ~941 J.
확인 예제 1–3 arithmetic on the potential 에너지 calculator.
위치 에너지 vs 운동 에너지
PE depends on height; kinetic 에너지 depends on 속력: KE = ½ m v². At the top of a throw, PE is high and KE is low; just before impact (ignoring air 저항), KE is high and PE is lower relative to the ground.
비교 with how to 계산 kinetic 에너지 and the
Spring 에너지 is different: elastic potential 에너지 U = ½kx².
흔한 실수
무료 위치 에너지 계산기
Use the free potential 에너지 calculator to solve PE = mgh for 에너지, 질량, or height with unit-aware inputs and 단계별 일ing.
일 calculator — lifting against gravity is 일 that shows up as PE.
무게 calculator — W = mg before PE = W h.
Gravitational 힘 calculator — when you leave the near-surface model.
Master PE = mgh with a clear zero height and consistent SI 단위 — then verify every home일 answer on the calculator.