Selina Concise ICSE Solutions For Class 8 Physics Chapter – 4 – Energy • When we are pushing a wall we are not doing any work as the position of wall is not change i.e. wall has not moved in the direction of force. • WORK: “is said to be done if on applying force on a body, the body moves (or changes it position) from it place in the direction of force. W = F × d Or “Work is said to be done by a force applied on a body, if it changes its size or shape.” • FACTORS AFFECTING THE AMOUNT OF WORK DONE : W = F × d (i) Magnitude of force applied. (ii) Distance moved by the body in the direction of force. UNIT OF WORK : W = F × d s.i unit W= 1N × 1m = Nm = joule (J) 1 kgf = 9.8 N is force on 1 kg ∴ F = mg Work done – 1 kgf × m = 9.8 N m = 9.8 J = 10 J nearly • A cooli standing with a box on his head, does no work as distance moved is...
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