# Solve the Mystery of Force 2 on a 2.43 kg Box

• copypacer
In summary, the conversation discusses finding the second force on a 2.43 kg box given a known force (F1), acceleration (a), and angle (θ). The attempt at a solution involves using vector notation and trigonometry, but the correct approach is to resolve the forces into components. This basic concept is necessary to solve the problem.
copypacer

## Homework Statement

There are two forces on the 2.43 kg box in the overhead view of the figure but only one is shown. For F1 = 20.0 N, a = 11.4 m/s2, and θ = 33.0°, find the second force (a) in unit-vector notation and as (b) a magnitude and (c) a direction. (State the direction as a negative angle measured from the +x direction.)The acceleration is in the third quadrant.

## Homework Equations

So, I used F2 = m(a) - F1. To try and find Force 2 and used cos and sin to fine it in vector notation. Apparently I got that wrong, HELP!

## The Attempt at a Solution

I used cos and sin to fine it in vector notation. Apparently I got that wrong, HELP!

So for a I got F2 = 2.43 * 11.4 - 20 which resulted in 7.03 or something and pluged that into (7.03 sin 33 degrees) and to find (j) and did the same with cos to find (i)

It didn't work, and magnitude and direction ended up being wrong because a) was wrong HEEEELP

#### Attachments

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With no diagram, the set-up is far from clear. Is the given angle the angle between F1 and the acceleration?
If so, it makes no sense to subtract F1 from ma as mere numbers. You can only do scalar addition and subtraction for vectors in the same direction.
Think about the net force in the direction of acceleration and the net force at right angles to that.

haruspex said:
With no diagram, the set-up is far from clear. Is the given angle the angle between F1 and the acceleration?
If so, it makes no sense to subtract F1 from ma as mere numbers. You can only do scalar addition and subtraction for vectors in the same direction.
Think about the net force in the direction of acceleration and the net force at right angles to that.
here it is, sorry

#### Attachments

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copypacer said:
here it is, sorry
Ok, my guess was almost right, and my comments stand.

copypacer said:
here it is, sorry
Wait I'm confused D:

Both the acceleration and force 2 are in the third quadrant, so its negative, wouldn't I still use F2 = ma - F1

so what do I do, since the two forces are not in the same direction?

I don't get it DX

haruspex said:
Ok, my guess was almost right, and my comments stand.
I'm trying to find the second force, so how would I solve that?

copypacer said:
Wait I'm confused D:

Both the acceleration and force 2 are in the third quadrant, so its negative, wouldn't I still use F2 = ma - F1

so what do I do, since the two forces are not in the same direction?

I don't get it DX
Do you know how to resolve a force into components?

haruspex said:
Do you know how to resolve a force into components?

...no...wait...no I don't

copypacer said:
...no...wait...no I don't
Well, that's rather basic, and I don't know how you would be expected to solve this problem without having been taught that.
There's a lots of stuff on the net. Try one of these:
http://www.physicsclassroom.com/class/vectors/Lesson-3/Resolution-of-Forces

http://www.s-cool.co.uk/a-level/phy...n/revise-it/resolving-vectors-into-components
As I said, in the present problem you need to resolve the given force into a component in the direction of acceleration and another at right angles to that.

## 1. What is the formula for calculating force?

The formula for calculating force is F = ma, where F is force, m is mass, and a is acceleration.

## 2. How do you determine the force on a 2.43 kg box?

To determine the force on a 2.43 kg box, you first need to determine the acceleration acting on the box. Then, using the formula F = ma, you can calculate the force by multiplying the mass (2.43 kg) by the acceleration.

## 3. How can I find the acceleration on a 2.43 kg box?

The acceleration on a 2.43 kg box can be found by dividing the net force acting on the box by its mass. This can be expressed as a = F/m.

## 4. What is the unit of force?

The unit of force is Newton (N), which is equivalent to kg*m/s^2.

## 5. How does the force on a 2.43 kg box affect its motion?

The force on a 2.43 kg box affects its motion by causing an acceleration in the direction of the force. The greater the force, the greater the acceleration and therefore the faster the box will move.

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