Forces of 11.5 N north, 20.4 N east, and 15.7 N south are simultaneously applied to a 3.74 kg mass as it rests on an air table. What is the direction of the acceleration in degrees? (Take east to be 0 degrees and counterclockwise to be positive.)

add the forces vectors.

a= F/m

combine the N-S forces, leaving you a S force, add that to E.

It's asking for the direction of acceleration. I calculated the acceleration already.

Use the two force vectors to get it.

YOu have a net S force, and a net E force.

tHe angle S of east is given by arctan S/E where S and E are the resultant vectors in those directions.

To find the direction of acceleration, we need to first find the net force acting on the mass. The net force is the vector sum of all the individual forces.

Given:
Force north (F_north) = 11.5 N, pointing in the y-direction (positive y-axis).
Force east (F_east) = 20.4 N, pointing in the x-direction (positive x-axis).
Force south (F_south) = 15.7 N, pointing in the negative y-direction.

Now, let's break down the individual forces into their x and y components:

F_north has no x-component and a positive y-component of 11.5 N.
F_east has a positive x-component of 20.4 N and no y-component.
F_south has no x-component and a negative y-component of 15.7 N.

Next, we can add up the x and y components of the forces separately to find the net force:

Net force in the x-direction (F_net_x) = F_east = 20.4 N (since it is the only force in the x-direction).

Net force in the y-direction (F_net_y) = F_north - F_south = 11.5 N - 15.7 N = -4.2 N.

So, the net force acting on the mass is F_net = F_net_x î + F_net_y ĵ, with F_net_x = 20.4 N and F_net_y = -4.2 N.

Now, let's find the magnitude and direction of the net force:

Magnitude of the net force (F_net) = √(F_net_x^2 + F_net_y^2)
= √((20.4 N)^2 + (-4.2 N)^2)
= √(416.16 N^2 + 17.64 N^2)
= √(433.80 N^2)
= 20.84 N (approximately)

Direction of the net force (θ_net) can be found using the inverse tangent function (tan^(-1)):

θ_net = tan^(-1)(F_net_y / F_net_x)
= tan^(-1)(-4.2 N / 20.4 N)
= tan^(-1)(-0.205)

Using a scientific calculator or trigonometric table, we find that tan^(-1)(-0.205) is approximately -11.71 degrees.

Since the question asks for the direction of acceleration, and acceleration is in the direction of the net force, the direction of acceleration in degrees is -11.71 degrees.