# Homework Help: Newton's Laws of Motions

1. Oct 2, 2016

### Morrissey

1. The problem statement, all variables and given/known data
One or more external forces are exerted on each object enclosed in a dashed box shown in the figures below. Identify the reaction to each of these forces, assuming that (b) occurs on Earth. Select all that apply.

(b) the wagon exerts a force

· downward on the Earth due to contact
· downward on the Earth due to gravitational attraction
· upward on the Earth due to gravitational attraction
· upward to the left on the handle (???)
· upward on the Earth due to contact

(My choices in underline)
3. The attempt at a solution

The main question I have about this problem is whether the wagon exerts a force upwards to the left on the handle. I thought that the wagon would exert a force downwards to the left on the handle, but this isn't an answer choice, so I thought that selection would be a trick question.

Last edited by a moderator: Oct 2, 2016
2. Oct 2, 2016

### BvU

Hi Morrissey,

(better to keep one exercise per thread -- less confusing)

Thread 2: when $m_1$ is at rest, the maximum friction force is $\mu_s N = \mu_s m_1 g$; you must first check if the driving force $m_2 g$ can exceed this.

3. Oct 2, 2016

### Staff: Mentor

Note: the second exercise has been removed from this thread. The OP is invited to post it in a separate thread.