# Solved: Force Problem x-axis [SOLVED] Force Problem

• Cursed
In summary, the problem asks to find the magnitude and direction of acceleration for an object with a mass of 3.00 kg, given that only two forces (40N and 60N) are acting on it. The correct solution is found by calculating the resultant force using vector addition and then using the F=ma equation. The attempts at finding the solution by taking the average, using Pythagorean theorem, and using R = r-r0 were incorrect. The correct method is to find the x and y components of each vector, add them up, and use Pythagorean theorem to find the magnitude of the resultant force.
Cursed
[SOLVED] Force Problem

## Homework Statement

Only two forces act on an object (mass = 3.00 kg), as in the drawing (below). Find the magnitude and direction (relative to the x-axis) of the acceleration of the object.

http://img148.imageshack.us/img148/6302/imgfbic2.png

F=ma

## The Attempt at a Solution

F=ma
40N=(3.00kg)(a)
13.33m/s/s=a

Correct answer: 30.9m/s/s, 27.2 degrees above the +x axis.

Last edited by a moderator:
there are two forces acting on it so you would have to find the resultant force because you have to find the force net in order to use the F=ma equation. Finding the resultant by using vector addition method will give you the Force net and then you can plug in the mass to solve.

princesspriya said:
there are two forces acting on it so you would have to find the resultant force because you have to find the force net in order to use the F=ma equation. Finding the resultant by using vector addition method will give you the Force net and then you can plug in the mass to solve.

I understand what you're saying, but I'm confused. I thought I knew how to calculate the resultant vector, but the way I'm calculating it leads me to the wrong answer.

Can you please show me how to do it? I would greatly appreciate it. ;)

Show how you calculated the resultant.

Doc Al said:
Show how you calculated the resultant.

Okay.

I tried THREE ways:

1. I averaged the two vectors: .5(60N+40N) = 50N... Then I divided by 3 (since the weight is 3.00kg and F=ma). That equaled 16 and 2/3 m/s/s. Wrong.

2. I found the y component via Pythagorean theorem. It was √2000 = 44.7214N. Then I divided by 3 for the same reasons as #1. That equaled 14.97 m/s/s. Wrong.

3. I did R = r- r0. (R being the resultant vector I am trying to find.). R = 40N. I divided it by 3 and got 13 and 2/3 m/s/s. Wrong.

Why in the world would you (attempt to) take the average?

In any case, do this: Find the x & y components of each vector. Add up the x components: that will be the x component of the resultant. Do the same with y components to find the y component of the resultant.

You can then find the magnitude of the resultant via the Pythagorean theorem.

you have to split the 60 N into two different vector quantities since it has a horizontal and vertical magnitude. the 40 N only has a horizontal quantity. then you would add the horizontal component of 60 and 40 to get the total force in the x direction.

Doc Al said:
Why in the world would you (attempt to) take the average?

Haha, because none of the other ways I did it worked.

Doc Al said:
In any case, do this: Find the x & y components of each vector. Add up the x components: that will be the x component of the resultant. Do the same with y components to find the y component of the resultant.

You can then find the magnitude of the resultant via the Pythagorean theorem.

Thank you. I finally got the answer. :]

princesspriya said:
you have to split the 60 N into two different vector quantities since it has a horizontal and vertical magnitude. the 40 N only has a horizontal quantity. then you would add the horizontal component of 60 and 40 to get the total force in the x direction.

Thank you for your help too. :]

## 1. What is the formula for calculating force on the x-axis?

The formula for calculating force on the x-axis is Fx = m * ax, where Fx is the force on the x-axis, m is the mass of the object, and ax is the acceleration on the x-axis.

## 2. How do I determine the direction of the force on the x-axis?

The direction of the force on the x-axis is determined by the direction of the acceleration on the x-axis. If the acceleration is positive, the force is in the positive direction; if the acceleration is negative, the force is in the negative direction.

## 3. What are some common units for force on the x-axis?

Some common units for force on the x-axis include Newtons (N), kilograms (kg), and meters per second squared (m/s^2).

## 4. Can I use the same formula for calculating force on the y-axis?

No, the formula for calculating force on the y-axis is Fy = m * ay, where Fy is the force on the y-axis, m is the mass of the object, and ay is the acceleration on the y-axis. This formula is different because the force and acceleration are acting on a different axis.

## 5. How can I apply the concept of force on the x-axis in real-life situations?

The concept of force on the x-axis can be applied in various real-life situations, such as calculating the force needed to push a box across a surface, determining the force needed to accelerate a car to a certain speed, or calculating the force needed to lift an object using a pulley system.

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