How hard must someone pull on the unkown line and inwhat direction to keep the knot from moving

4.4N, 263.4°

Step-by-step explanation:

The sum of all forces must add to zero:

The forces in the x-plane:

∑F = 3N + (cos 120°)*5N + x = 0

x = -(3N + (cos 120°)*5N)

x = -0.5N

The forces in the y-plane:

∑F = (sin 120°)*5N + y = 0

y = -(sin 120°)*5N = -√(3/4)*5N = -4.3N

The magnitude of the unknown force U is:

U = √(x² + y²) = √19 = 4.4N

The direction is given by:

tanФ = y/x

Ф = 263.4°

answer: 0

step-by-step explanation: the positive, like 5, + its opposite, like -5 would be 0

5+(-5)=0, or 5-5=0