Question

find the moment about the point (1,-1,-1)of the force 3i^+4j^-5k^ acting at the point (1,0,-2).

Answer 1

Answer:

-1i^-3j^-3k^

Explanation:

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Answer 2

Answer:

The moment about the point (1,-1,-1)of the force (3i+4j-5k) acting at the point (1,0,-2) is (-i -3j -3k) .

Explanation:

Given that :

• Point A = (1, -1, -1)
• Point B = (1, 0, -2)
• Force, F = (3i + 4j - 5k)

Solution :

• The moment of force about an axis of rotation is called the torque.
• Torque associated with a force, F acting on a particle which is moving about a point is defined as
• τ = r x F
• where, r is the position vector of the particle.
• The position vector, r of the particle is = BA
• r = (i - 2k)- (i - j - k) = ( j - k )
• The force, F along the particle is (3i + 4j - 5k)
• Torque, τ = ( j - k ) x (3i + 4j - 5k)
• τ = i(-5+4) - j(3) + k(-3)
• τ = (-i -3j -3k) .
• Hence , the moment of the given force is (-i -3j -3k)