It's difficult to make out what the force and displacement vectors are supposed to be, so I'll generalize.
Let <em>θ</em> be the angle between the force vector <em>F</em> and the displacement vector <em>r</em>. The work <em>W</em> done by <em>F</em> in the direction of <em>r</em> is
<em>W</em> = <em>F</em> • <em>r</em> cos(<em>θ</em>)
The cosine of the angle between the vectors can be obtained from the dot product identity,
<em>a</em> • <em>b</em> = ||<em>a</em>|| ||<em>b</em>|| cos(<em>θ</em>) ==> cos(<em>θ</em>) = (<em>a</em> • <em>b</em>) / (||<em>a</em>|| ||<em>b</em>||)
so that
<em>W</em> = (<em>F</em> • <em>r</em>)² / (||<em>F</em>|| ||<em>r</em>||)
For instance, if <em>F</em> = 3<em>i</em> + <em>j</em> + <em>k</em> and <em>r</em> = 7<em>i</em> - 7<em>j</em> - <em>k</em> (which is my closest guess to the given vectors' components), then the work done by <em>F</em> along <em>r</em> is
<em>W</em> = ((3<em>i</em> + <em>j</em> + <em>k</em>) • (7<em>i</em> - 7<em>j</em> - <em>k</em>))² / (√(3² + 1² + 1²) √(7² + (-7)² + (-1)²))
==> <em>W</em> ≈ 5.12 J
(assuming <em>F</em> and <em>r</em> are measured in Newtons (N) and meters (m), respectively).
There would be 1,320 different ways, just multiply all the possible front runners 12 second runners 11 and third runners 10, 12x11x10=1,320
Answer:
16
Step-by-step explanation:
If you would like to know how many gallons of paint will Henry need to paint his living room, you can calculate this using the following steps:
the ceiling: 24 ft * 18 ft = 432 ft squared
walls: 2 * 24 ft * 9 ft + 2 * 18 ft * 9 ft = 2 * 24 * 9 + 2 * 18 * 9 = 432 + 324 = 756 ft squared
432 ft squared + 756 ft squared = 1188 ft squared
1 gallon of paint ... 450 ft squared
x gallons of paint = ? ... 1188 ft squared
1 * 1188 = 450 * x
1188 = 450 * x /450
x = 1188 / 450
x = 2.64 gallons of paint
The correct result would be 2.64 gallons of paint.
