Question

Force acting on a particle is (2`hat"i"` + 3 `hat"j"`) N. Work done by this force is zero, when a particle is moved on the line 3y + kx = 5. Here value of k is ______.

Options

• 2

• 4

• 6

• 8

Answer 1

Force acting on a particle is (2`hat"i"` + 3 `hat"j"`) N. Work done by this force is zero, when a particle is moved on the line 3y + kx = 5. Here value of k is 2.

Explanation:

Force is parallel to a line y = `3/2x+"c"`

The equation of given line can be written as

y = `-"k"/3x+5/3`

When force is perpendicular to displacement, i.e. the above two lines are perpendicular, work done is zero or

m₁m₂ = –1

or `(3/2) (-"k"/3)` = -1

or k = 2