Weight, Mass and g: W = mg Worked Examples | GCSE Physics

Weight and mass for GCSE Physics, animated: why an astronaut weighs about a sixth as much on the Moon but has exactly the same mass. Mass is the amount of matter, in kilograms; weight is the force of gravity on it, in newtons, and you measure it with a newtonmeter (a calibrated spring balance). Then W = mg with the value of g each board uses (AQA gives it in the question, usually 9.8 N/kg; Edexcel and OCR use 10 N/kg), and weight is directly proportional to mass. Four worked examples: a 65 kg student on Earth (637 N) and on the Moon (104 N), rearranging to find a suitcase's mass (6.0 kg), and an apple in grams (2.45 N). Plus gravitational fields (all matter has one, OCR), the centre of mass (AQA), and four mistakes that cost marks. Covers: AQA 4.5.1.3 (Combined 6.5.1.3) · Edexcel 2.16–2.18 · OCR Gateway P2.3g–h, P2.3j (Foundation and Higher, Combined Science and separate Physics; P2.3j is OCR separate Physics only). 0:00 Intro 0:08 Hook 0:42 Mass and weight 1:15 Measuring weight 1:50 W = mg 2:39 Worked example: a student's weight 3:13 Worked example: on the Moon 3:47 Worked example: finding a mass 4:20 Worked example: grams first 4:57 Gravitational fields 5:38 Centre of mass 6:08 Common mistakes 6:35 Summary Narrated with an AI voice. Worked Example is not affiliated with or endorsed by AQA, OCR or Pearson Edexcel. Exam board names are used only to show which specifications a video covers.