MHT CET2007MathematicsVector Algebra
If the constant forces 2 i -5 j +6 k and - i +2 j - k act on a particle due to which it is displaced from a point A(4,-3,-2) to a point B(6,1,-3) , then the work done by the forces is
Options
- A15 unit
- B9 unit
- C-15 unit
- D-9 unit
Correct answer
C. -15 unit
Step-by-step solution
Resultant force, F =(2 i -5 j +6 k )+(- i +2 j - k )= i -3 j +5 k Displacement, aligned d = A B &=(6 i + j -3 k )-(4 i -3 j -2 k ) &=2 i +4 j - k W &= F d =( i -3 j +5 k ) (2 i +4 j - k ) &=2-12-5=-15 unit aligned