Suppose you exert an upward force Fi to the handles of a...

Suppose you exert an upward force Fi to the handles of a wheelbarrow at a distance of li = 1.50 m to the left of the contact point between the wheel and the ground as shown in the figure below. The center of gravity of the loaded wheelbarrow is located at a distance of lo = 10.0 cm to the left of the contact point between the wheel and the ground. What upward force Fi must you exert to support the wheelbarrow and its load if their combined weight is 300 pounds? Assume 3 significant digits in your answer and assume units of pounds. Answer: 20 lb

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Transcript

00:02 So in this question we are given a wheelbarrow and loaded wheelbarrow and we are told that the loaded wheelbarrow weight.

00:10 So this is the weight.

00:13 So the mass of this thing is 300 pounds.

00:18 And the weight or the mass acts at the cg which is located at l0, which is given to be as 10 centimeters or we'll take it in meters as 0 .1 meters.

00:33 And there's a reaction force over here at the wheel itself from where the pivot, this is the pivot point.

00:40 So, and there is a force fi, which we must exert to support the system in this given condition.

00:48 And the distance where we apply the force is given to us as 1 .5 meters.

00:56 And we are asked to find this fi.

00:58 And also we are asked to find the fi in terms of equivalent weight.

01:01 So basically fi is needed to be in pounds, not in pound force.

01:08 So let's first look at the condition here.

01:12 So there's a normal force reaction.

01:14 So this normal force is going through the pivot point.

01:17 So it will not have any.

01:19 I mean, if you do force balance, you will see that w in the vertical direction down is equal to fi plus the normal force.

01:28 And this is not useful because fi and n both are not known.

01:33 So what will help us is moment balance instead of weight balance...

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