Can someone quickly clarify the answer for this?

[Lori]

Homework Statement

Two forces are applied to a 5.0 kg object, one is 6.0 N to the north and the other is 8.0N to the west. What is magnitude of the acceleration of the object?

1. .5 m/s2
2. 2.0
3. 2.8
4. 10
5. 50

The answer is 2) 2.0 m/s^2 buttt

Homework Equations

Fnet = ma

The Attempt at a Solution

When i drew the free body diagram, i put the weight of the object as another force , but apparently, that is not correct and the only two forces would be the ones given. .. Why can't i include the force due to gravity? Isn't not implied in this problem? (This is a question from a physics exam)

I mean cause the problems gives the object mass... so wouldn't it have force due to gravity? I'm just scared that ill mess this up on the real exam...

 

[Lori]

 

[stockzahn]

Where do you get the answer 2 m/s² from?

 

[Lori]

For the first diagram which would be the correct one has Fnet = 10. So a = 10/5 = 2.0m/s.

If I did it for the other diagram with Fg... then a = around 8 which isn't an answer

 

[stockzahn]

For the first diagram which would be the correct one has Fnet = 10. So a = 10/5 = 2.0m/s.

If I did it for the other diagram with Fg... then a = around 8 which isn't an answer

Well, I think you've understand how to find the correct answer - with and without gravity. To find an unambiguous text for a question in an exam is not always easy. But you found the correct question by comparing the answers. Be confident for the exams, you could write both solutions and questions regarding the task normally should be answered. Of course, there is no guarantee not to misunderstand the question with all the assumptions and simplifications made.

 

[Lori]

Well, I think you've understand how to find the correct answer - with and without gravity. To find an unambiguous text for a question in an exam is not always easy. But you found the correct question by comparing the answers. Be confident for the exams, you could write both solutions and questions regarding the task normally should be answered. Of course, there is no guarantee not to misunderstand the question with all the assumptions and simplifications made.

Understood! :) Thanks!

 

[haruspex]

Why can't i include the force due to gravity?

It is not clear from your diagram which directions the three forces are in. If you include gravity they will be mutually at right angles, but it looks like you have the 6N and mg both vertical. You should have got 10.1.
I agree that the question should have stated "... resting on a smooth horizontal floor".