Calculating Net Force on 2kg Mass Down 8m Incline

[NickS606]

Homework Statement

A 2kg mass starts from rest and slides down an inclined plane 8.0X10m long in 0.50s. What net force is acting on the mass along the incline?

Homework Equations

The Attempt at a Solution

I don't even know where to begin.

 

[Delphi51]

This is an accelerated motion problem. Use a motion formula to find the acceleration.

 

[Dr.D]

Try drawing a free body diagram and then sum the forces on the body.

 

[NickS606]

I'm sorry I am still new, can I get a better explanation please?

 

[Hootenanny]

I'm sorry I am still new, can I get a better explanation please?

Can you work out the acceleration of the object?

 

[NickS606]

How can I do that?

 

[Hootenanny]

How can I do that?

Do you know any Kinematic (SUVAT) equations?

 

[NickS606]

I'm just going to go ahead and say I have never even heard of those equations.

 

[Hootenanny]

I'm just going to go ahead and say I have never even heard of those equations.

Really? Then I'm going to go ahead and say take a look in your textbook or class notes and find them.

Alternatively, you can find them https://www.physicsforums.com/showpost.php?p=905663&postcount=2". However, I must say that I will be extremely surprised if your teacher hasn't mention them, but set you a homework that requires them.

 

[NickS606]

Ya I don't really recall those. Anyways, would I do $$a_{ave} = \Delta v / \Delta t$$

I did 12N/3.5s and my answer is 3.4, is this correct?

 

[Hootenanny]

Ya I don't really recall those. Anyways, would I do $$a_{ave} = \Delta v / \Delta t$$

Perhaps, but we'll have to do some work first.

I did 12N/3.5s and my answer is 3.4, is this correct?

No. Did you just pluck those numbers out of thin air?

Returning to the question, what do the dimensions 8x10m refer to? Height and width or height and hypotenuse or width and hypotenuse? Do you have a diagram?

 

[NickS606]

I got the numbers out of the question, and there is no diagram, it is height and width for sure though.

 

[Hootenanny]

I got the numbers out of the question, and there is no diagram, it is height and width for sure though.

Okay. Have you looked for the kinematic equations in your notes or text?

 

[NickS606]

Well there aren't many notes and all I could find was this equation $$v_{ave} = \Delta x / \Delta t$$

The teacher isn't really that great and won't help much, that's why I am here.

 

[Hootenanny]

Well there aren't many notes and all I could find was this equation $$v_{ave} = \Delta x / \Delta t$$

Okay, well we cannot use that equation. Try reading http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/1DKin/U1L6a.html" and see if it jogs your memory.

 

[NickS606]

I'm just not getting it, I assume the equation to be used is

d=vi*t+1.5*a*t^2

 

[Hootenanny]

I'm just not getting it, I assume the equation to be used is

d=vi*t+1.5*a*t^2

The highlighted coefficient should be 0.5 rather than 1.5, but yes, this is the equation to use. Can you start filling in the known variables?

 

[Delphi51]

Yes, that formula will do it if the initial velocity is zero.

 

[NickS606]

Is it d=0*.50s+.5*a*.50s^2

I put a for acceleration because I don't know what acceleration is :/

 

[Hootenanny]

Yes, that formula will do it if the initial velocity is zero.

One may use the above formula even if the initial velocity is non-zero.

Is it d=0*.50s+.5*a*.50s^2

I put a for acceleration because I don't know what acceleration is :/

Acceleration is what you want to find out! You need to solve for the acceleration.

Now, what about the distance traveled?