Wednesday

April 16, 2014

April 16, 2014

Posted by **Mitch** on Saturday, March 6, 2010 at 8:29pm.

It wants me to find the work. now i know w=Fxdr. what i want to know is why when you take the dot product of both, you get a different answer compared to when you just multiply the magnitudes.

- physics -
**drwls**, Saturday, March 6, 2010 at 8:36pmIt is called a dot product, but you typed it like a cross product, which is something else entirely.

The dot product of two vectors is the product of their magnitudes TIMES the cosine of the angle between the vectors. These vectors are not parallel in this case, so the cosine is less than 1.

In your case, the cross product is 16, and the product of the magnitudes is 19.41. The cosine of the angle between the vectors is 0.824. There is a 34.5 degree angle between them.

**Related Questions**

physics - A particle moving in the xy plane under goes displacement s=(2i+3j)m ...

Physics - Help a constant force equal to (5i+2j)N moves a particle through a ...

physics - A=2i+3j-k, b=4i=2j-2k, find the vector x parallel to A but has ...

algebra - Find the angles between the following pairs of vectors (1)3i+2j-6k,4i-...

algebra - Find the angles between the following pairs of vectors (1)3i+2j-6k,4i-...

trig - U=5i+11j and V=2i-3j, find 2U-7U

maths - The vector equations of 2 beams of light r1 and r2 in 3 dimensional ...

Vectors - Vectors "v" and "w" are given by v = 5i - 2j and w = i + 3j. Find ...

Help on Vectors & Geometry - (a) Given that A= 3i - j + 2k and B=2i + 3j - k ...

IB Math SL - Find a unit vector which is perpendicular to both of the vectors 4i...