Question

as shown in the diagram below, an open box and its contents have a combined mass of 5.0 kilograms. a horizontal force of 15 newtons is required to push the box at a constant speed of 1.5 meters per second across a level surface.
the inertia of the box and its contents increases if there is an increase in the
(1) speed of the box
(2) mass of the contents of the box
(3) magnitude of the horizontal force applied to the box
(4) coefficient of kinetic friction between the box and the level surface
39.
a child pulls a wagon at a constant velocity along a level sidewalk. the child does this by applying a 22 - newton force to the wagon handle, which is inclined at 35° to the sidewalk as shown below.
what is the magnitude of the force of friction on the wagon?
(1) 11 n
(2) 13 n
(3) 18 n
(4) 22 n

Explanation:

Step1: Analyze the horizontal force component

Since the wagon is moving at a constant velocity, the net force in the horizontal direction is zero. The horizontal component of the applied force \(F_{applied - x}=F\cos\theta\), where \(F = 22N\) and \(\theta=35^{\circ}\). According to Newton's first law, the frictional force \(F_f\) is equal to the horizontal component of the applied force.

Step2: Calculate the horizontal component

Using the formula \(F_f = F\cos\theta\), substitute \(F = 22N\) and \(\theta = 35^{\circ}\). We know that \(\cos35^{\circ}\approx0.819\). Then \(F_f=22\times0.819 = 18.018N\approx18N\)

Answer:

(3) \(18N\)