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vekshin1
3 years ago
11

Why can't speed ratio ever equal mechanical advantage?

Physics
1 answer:
OLga [1]3 years ago
6 0
Efficiency of a simple machine is the ratio of mechanical advantage and speed ratio.

If mechanical advantage = speed ratio then efficiency = 1
Which is impossible for a practical machine due to presence of frictional force which wastes some energy and thus lowers the output
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Consider an elevator with a table and a book on top of the table. The mass of the table is 10kg and the mass of the book is 2kg.
Step2247 [10]

Newton's second law allows us to find the force of the block on the table is 126 N

Newton's second law says that the net force is proportional to the product of the mass and the acceleration of the body

                Σ F = m a

Where the bold letters indicate vectors, m is the mass and the acceleration of the body

A free body diagram is a diagram where the forces are represented without the details of the bodies, in the attached we can see a free body diagram of the system.

Let's start by finding the acceleration of the elevator with kinematics  

                 v = v₀ + a t

                 a = \frac{v-v_o}{a}  

Where v and v₀ are the current and initial velocity, respectively, at acceleration and t is the time

                 a = \frac{8-1}{2}

                 a = 3.5 m / s²

Let's write Newton's second law for each body

The book

                N₂ - W₂ + N₁ = m a

               

Table

                N₁ - W₁ - W₂ = M a

                W₁ = Mg

                W₂ = mg

                N₁ = (M + m) g + M a

                N₁ = (10 + 2) 9.8 + 10 3.5

                N₁ = 152.6 N

This is the reaction of the earth to the support of the block and the table

               N₂ = ma + m g  - N₁

               N₂ = m ( a +g) - N₁  

               N₂ = 2 (3.5 + 9.8) - 152.6

               N₂ = 26.6 - 152.6

               N₂ = -126 N

The negative sign indicates that the direction is opposite to the one assigned, this is the action of the block on the table.

In conclusion using Newton's second law we can find the forces of the block on the table is 126 N

Learn more here: brainly.com/question/19860811

4 0
2 years ago
12) A neutral atom has two, eight, eight electrons in its first, second, and third energy levels.This information ________.
pentagon [3]

Answer:

C.

Explanation:

Option C

The information given in the question tells us about the number of electrons in an atom and also the number of shells in the atom. So, we will come to know about the atomic number, size and chemical properties of the atom. But we cannot determine atomic mass. Atomic mass is a function of number of neutrons and protons.

3 0
3 years ago
According to the Big Bang Theory, how long ago did the universe expand explosively into existence
Dmitry_Shevchenko [17]

About 13.7 billion years ago

The Big Bang Theory states that the universe started about 13.7 billion years ago, and before that, everything was in 1 singularity.



3 0
3 years ago
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Discuss why Wolpert says we have a brain.
ycow [4]

Answer:

“We have a brain for one reason and one reason only, and that's to produce adaptable and complex movements,” stated Wolpert, Director of the Computational and Biological Learning Lab at the University of Cambridge. ... The evidence for this is in how well we've learned to mimic our movements using computers and robots.

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Why is it very difficult for astronomers to find objects like planets and asteroids?
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It is difficult for astronomers to find object like planets and asteroids because it takes a lot of time to verify the objects locations and what surrounds a certain object in order to prove and be precise of its location
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