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horsena [70]
3 years ago
10

A uniform 2.50m ladder of mass 7.30kg is leaning against a vertical wall while making an angle of 51.0degree with the floor. A w

orker pushes the ladder up against the wall until it is vertical.
A)How much work did this person do against gravity?
____J
Physics
1 answer:
Zigmanuir [339]3 years ago
8 0

Answer:

19.95 J

Explanation:

The center of mass of the ladder is initially at a height of:

h_1=\frac{L}{2}sin\theta

The center of mass of the ladder ends at a height of:

h_2= \frac{L}{2}sin90 =L/2

So, the work done is equal to the change in potential energy which is:

W = PE = mg(h_2-h_1)

now h_2-h_1= 1-sin\theta

therefore

W = [mgL/2]×[1 - sin(theta)]

W = [(7.30)(9.81)(2.50)/2]×[1-sin(51°)]

solving this we get

W = 19.95 J

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Alice is going on a picnic and is aware that it will be easier to carry the picnic basket if it balances at the center where the
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Answer: 13.703cm from the center of the basket on the end holding the 0.675kg package of hot dog.

Explanation:

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52cm/2.

The principle of moments is very important in solving this problem,

"The algebraic sum of all clockwise moments must be equal to he algebraic sum of all anticlockwise moments"

The statement above is the principle of moments.

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Therefore from the expression above, x = 13.703cm from the center on the basket on the side which holds the 0.675kg package of hot dog.

PS: The knowledge of moments of forces is very important in understanding machines especially those which are used for measuring weights relative to other weights.

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