# Physics/ Engineering

posted by .

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.

vector r1= (7,2,2) - (5,4,3) = 2i-2j-5k

vector r2= (3,2,5) - (5,4,3) = -8i-6j+2k

Vector M1= (2i-2j-5k) X P = -7i-7j+2k
Magnitude= 7.55 ft-lbs

Vector M2= (-8i-6j+2k) X Q = -2i-6j+85k
Magnitude= 86.23 ft-lbs

Moment about the given point = (7.55) + (86.23) = 93.78 ft-lbs

I'm unsure if this is right

## Similar Questions

1. ### 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 …
2. ### PHYSICS

The acceleration of the center-of-mass 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
3. ### 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 …
4. ### 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?
5. ### 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) …
6. ### 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) …
7. ### 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 .
8. ### Physics

A 49-N 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 …
9. ### 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 …
10. ### 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 …

More Similar Questions