Jacob and Matthew are pulling a 20 kg box filled with chocolate along the ground, while Savannah is trying to pull it back in the other direction. Jacob is pulling with 50 N, Matthew with 40 N, and Savannah is pulling with 60 N in a negative direction. Draw an FBD; it should have 5 forces on it. Find the net Force. Then calculate the acceleration of the box. Lastly, calculate the acceleration if Mathew decides to run for his life and stop pulling.

Explanation:

N/B: Please see attached a rough sketch of the free body diagram for your reference.

From the diagram, the weight W is acting downward and the resultant R is in the positive direction

Given data

mass m=20kg

Forces

Jacob is pulling with 50 N,

Matthew with 40 N, and

Savannah is pulling with 60 N in a negative direction

Required

The net force

Net force= 50+40-(60)

               =90-60

               =30N in the possitive direction(in Jacob and Mathew's direction)

we know that F=ma

a=F/m

a= 30/20

a=1.5m/s^2

if Mathew decides to run for his life and stop pulling the net force will be

Net force=50-60=-10N (in Savannah's direction)

a=F/m

a=10/20

a=0.5m/s^2