関連ワード:  definition of work class 9th physics    definition of work class 9th science    define 1j of work class 9 physics    define work class 9th science    define work done class 9 physics    define 1 j of work class 9th science    define 1 joule of work class 9 science    what is work class 9 physics    definition of work in physics class 9    define work in physics class 9