Power of a Force: Find Power from Fv in 3s

[hendrix7]

Homework Statement

A force of 2i + 5j moves from (2,5) to (4,7) in 3 seconds. Find the power of the force.

Homework Equations

Power = Fv

The Attempt at a Solution

|F| = sqrt 29
v = (sqrt 8)/3
Power = 5.077 w

 

[phyzguy]

You need to write the velocity as a vector and take the dot product of F and v.

 

[Abhishek kumar]

B

Homework Statement

A force of 2i + 5j moves from (2,5) to (4,7) in 3 seconds. Find the power of the force.

Homework Equations

Power = Fv

The Attempt at a Solution

|F| = sqrt 29
v = (sqrt 8)/3
Power = 5.077 w

But i am getting 4.66

 

[haruspex]

Power = Fv

As @phyzguy points out, that equation is not correct. In vectors, $P=\vec F.\vec v=|\vec F| |\vec v| \cos(\theta)$, where θ is the angle between the vectors.

 

[hendrix7]

Thank you guys for putting me straight.