Dynamics question, test tommorrow

[Matt1234]

Dynamics question, test tommorrow :(

Hello, need some help on this one for the test. The solution is 3.9 m/s^2 in the book, I am not sure what i have done wrong.

Homework Statement

http://img196.imageshack.us/i/questionu.jpg/

Homework Equations

The Attempt at a Solution

Here is my attempt. sorry about the big X i was frustrated.

http://img269.imageshack.us/i/attempt.jpg/

 

[Matt1234]

hmmmmmmmmm, got it.

At the very end where i have Fnet = m a

m is actually (2.5 + 5.5)

 

[nlightner]

Hi there,

I understand that you are having trouble with a dynamics question and have a test tomorrow. It's great that you are seeking help and trying to find the solution.

From your attempt, it seems like you have correctly identified the forces acting on the object and have attempted to solve for the acceleration using Newton's Second Law (F=ma). However, there is a small mistake in your calculation.

The net force on the object should be equal to the mass (m) multiplied by the acceleration (a), not divided by it. So the correct equation would be:

Fnet = ma

Therefore, the correct solution would be:

Fnet = 20 kg * 1.95 m/s^2 = 39 N

I hope this helps and good luck on your test tomorrow! Remember to double check your calculations and equations before submitting your answers.