Answer to Question #296227 in Mechanics | Relativity for Pride

Question

A toolbox with contents has a mass of 200kg and stands horizontal floor. The static frictional coefficient between the floor and toolbox is 0,4

1. Calculate the minimum horizontal force a handyman has to apply to make the toolbox move.

2. An electric drill and hammer (with combined mass of 25kg) is removed from the toolbox by the handyman. Calculate the new force necessary to move the toolbox

Answer 1

Explanations & Calculations

• The minimum horizontal force required to move the object from rest is equal to the static friction force ($\small f_{static}=\mu_sR\qquad; R=mg$ ).

1)Hence for this case, it is

$\qquad\qquad \begin{aligned} \small F_{max}&=\small f_{max}=\mu_s R\\ &=\small \mu_s.mg\\ &=\small 0.4\times200\,kg\times9.8\,ms^{-2}\\ \end{aligned}$

2)

• Now what happens here is, the total mass that is meant to move is reduced ($\small m \downarrow$ ), so the static friction force would drop ($\small f_s \downarrow$ ) resulting in much less force to be applied ($\small F_m \downarrow$ ) before it could be moved.
• Following the same steps as for the previous case, you can calculate the required force.