Quick Physics Mechanics Question?

Question

Can someone break this down in steps for me that I can follow? I am lost, and would like to learn how to do the problem. Thank you!

Only two forces act on an object (mass = 2.80 kg), as in the drawing. (F = 53.0 N.) Find the magnitude and direction (relative to the x axis) of the acceleration of the object. magnitude

Answer 1

Okay, let's introduce a few key concepts:

A. Force vectors
B. Newton's Second Law

A. A force is a vector like any other, with the SI units of Newtons (1 N = kg*m/s/s). Inherently, you may notice that it's unit is mass (in kg) multiplied by acceleration. Keep in mind though, that both forces and accelerations are vector quantities.

B. The equation that let's us understand forces, masses, and accelerations (you're going to want to commit this one to memory):

Newton's Second Law:

Summation of force vectors = mass * acceleration of the object's vector.

Therefore:

The acceleration on the x-axis is the x-components of all your forces added, divided by the mass of the objects.

Since you've given us no idea what direction the forces are acting in, I'll assume that the *one* force you've given us (53 N) is in the positive X-direction. Feel free to adjust this to the actual question:

F1 + F2 + F3 .... = m*a

Only one force, ergo:

F1 = m*a

a = F1/m = (53 N)/(2.8 kg) = 18.9 m/s/s

Answer 2

Without the drawing I'm guessing. If the vectors are given as magnitude and angle, convert them to rectangular (x,y) coordinates. Add them. If the sum is expected as magnitude and angle, convert it back. Google "rectangular polar" if you're not familiar with the conversions.