Physics/ Engineering
posted by Aaron .
Calculate the moment about a point (5; 4; 3) ft. caused by the forces
P = 3^i  2^j  4^k lb. and Q = 5^i + 7^j  2^k lb. acting at the points
(7; 2; 2) ft. and (3; 2; 5) ft., respectively.
What I did was this;
vector r1= (7,2,2)  (5,4,3) = 2i2j5k
vector r2= (3,2,5)  (5,4,3) = 8i6j+2k
Vector M1= (2i2j5k) X P = 7i7j+2k
Magnitude= 7.55 ftlbs
Vector M2= (8i6j+2k) X Q = 2i6j+85k
Magnitude= 86.23 ftlbs
Moment about the given point = (7.55) + (86.23) = 93.78 ftlbs
I'm unsure if this is right
Respond to this Question
Similar Questions

physics (work posted)
For a body to be in equilibrium under the combined action of several forces. a) all the forces must be applied at the same point b) all of the forces form pairs of equal and opposite forces c) the sum of the components of all the forces … 
PHYSICS
The acceleration of the centerofmass point of a system of particles depends on: a) all the forces acting on the system b) only the external forces acting on the system c) only the internal forces acting on the system 
Physics
(10 points) 3. Use your data from Part 3 and Newtonâ€™s laws to explain why the force meter measures a force if the cart is moving at a constant velocity. The forces acting on the cart are the applied force (FA), the force of friction … 
Physics
A ball is falling through the air. It has just two forces acting on it, its weight and air resistance. Which of the following statements is true? 
Engineering
Calculate the moment about a point (5; 4; 3) ft. caused by the forces P = 3^i  2^j  4^k lb. and Q = 5^i + 7^j  2^k lb. acting at the points (7; 2; 2) ft. and (3; 2; 5) ft., respectively. What I did was this; vector r1= (7,2,2) … 
Engineering
Calculate the moment about a point (5; 4; 3) ft. caused by the forces P = 3^i  2^j  4^k lb. and Q = 5^i + 7^j  2^k lb. acting at the points (7; 2; 2) ft. and (3; 2; 5) ft., respectively. What I did was this; vector r1= (7,2,2) … 
physics
A jet plane is traveling at a constant speed in a straight line in level speed. What does this tell you about the forces acting on it, what forces are acting on it . 
Physics
A 49N force is applied perpendicular to the portion BC of the bent bar. Determine the moment of P about point B and about point A. The image shows a bar that is straight from point A to B but then bends at a 42 degree angle to the … 
Physics
A two dimensional object placed in the xy plane has three forces acting on it: a force of 3N along the x axis acting at a point (3m, 4m); A force of 2N along the y axis acting at (2, 5m); and a force of 5N in the negative x direction … 
Physics
A hemisphere of radius r is placed on a horizontal plane and a small mass of "m" is placed on the top of the hemisphere. Find the height from the ground to the mass m,at the moment it loses it's contact with the hemisphere.And the …