A body moves from a position r 1 = 2 i ^ - 3 j ^ - 4 k ^ m to a position, r 2 = ( 3 i ^ - 4 j ^ + 5 k ^ ) m under the influence of a constant force F = 4 i ^ + j ^ + 6 k ^ N . The work done by the force is

Question

A body moves from a position r 1 = 2 i ^ - 3 j ^ - 4 k ^ m to a position, r 2 = ( 3 i ^ - 4 j ^ + 5 k ^ ) m under the influence of a constant force F = 4 i ^ + j ^ + 6 k ^ N . The work done by the force is, 57 J, 58 J, 59 J, 60 J

MARKS App · Accepted Answer

Given, r 1 = 2 i ^ - 3 j ^ - 4 k ^ And r 2 = 3 i ^ - 4 j ^ + 5 k ^ Now, r 2 - r 1 = i ^ - j ^ + 9 k ^ And F = 4 i ^ + j ^ + 6 k ^ ∴ work done = F.r W = 4 i ^ + j ^ + 6 k ^ . ( i ^ - j ^ + 9 k ^ ) = 4 - 1 + 54 = 57 J

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