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3 years ago

What is the minimum force require to move a 5kg wooden crate on a wooden floor?

1 answer:

7 0

You need to know the coefficient of static friction between a wooden object and a wooden surface. I'll denote it with µ. If you're given a specific value you should obviously use that.

By Newton's second law, the horizontal and vertical net forces are

• net horizontal:

∑ F = p - f = 0

• net vertical:

∑ F = n - w = 0

where

p = magnitude of the pushing force

f = mag. of friction

n = mag. of the normal force

w = weight of the crate

The second equation gives

n = w = (5 kg) (9.8 m/s²) = 49 N

Friction is proportional to the normal force by a factor of µ, so

f = µ (49 N) = 49µ N

To overcome static friction, the push has to exceed this in magnitude, so that

p > 49µ N

For instance, if p = 0.25, then p would need to greater than 12.25 N. (This example isn't particularly helpful, though, since both possibly correct options are larger than 12.25 N...)

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What are the historical solar system models. Differences

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Aristarchus(310-230 BC)
Aristarchus was a Greek Astronomer and Mathematician. He proposed the heliocentric model of the Solar System. He attempted to measure the distances from the moon to the sun.
Aristotle (334-322 BC)
Aristotle was a Greek Philosopher. He was the first person to propose this historical model. He thought the Earth was in the center of all celestial beings. His idea was that the Earth was in the middle of the sun, moon, stars, and other planets. 
Ptolemy(100-170 CE)
Ptolemy was a astronomer and a geographer and a mathematician! He proposed the geocentric model. He believed that a celestial body could go at a constant speed in a perfect circle. It was called the "wheels-on-wheels" system. It had better observations than the model that had came before his. His geocentric model was used for the next 14 centuries! 
Kepler(1571-1630)
German astronomer and mathematician, Johannes Kepler, studied very hard and closely, and he found out that the planets did not fit the observations that were made by previous explorers. He found one that fit the best out of them all! He found three principles, called Kepler's Laws.

7 0

4 years ago

Which family (group) of elements rarely forms chemical bonds with other elements?

Masteriza [31]

VIII group or the noble gases

3 0

4 years ago

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The owner of a window treatment company wants to design Shades that will cover the windows of the house. the shades should also

prohojiy [21]

black and textured is the answer.

5 0

3 years ago

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A 1.94-m-diameter lead sphere has a mass of 5681 kg. A dust particle rests on the surface. What is the ratio of the gravitationa

scoundrel [369]

To develop this problem we will apply Newton's laws regarding gravitational forces, both in space and on earth. From finding this relationship, leaving the variable of the dust mass open, we will find the relationship of the forces between the two surfaces. Our values are,

$\text{Diameter of the lead sphere} = D=1.940m$

$\text{Mass of the lead sphere} = m_1 = 5681kg$

$\text{Mass of the dust particle} = m_2$

Distance between the center of lead sphere to dust particle

$r = \frac{D}{2}$

$r = \frac{1.940m}{2}$

$r = 0.97m$

Gravitational force of the sphere on the dust particle:

$F = \frac{Gm_1m_2}{r^2}$

$F = \frac{(6.67*10^{-11}N\cdot m^2/kg^2)(5681kg)(m_2)}{(0.97m)^2}$

$F = (4.027*10^{-7} N/kg)m_2$

Weight of the dust particle

$W = m_2 g$

$W = m_2 (9.8m/s^2)$

Ratio of F and W:

$\frac{F}{W} = \frac{(4.07*10^{-7}N/kg) m_2)}{m_2(9.8m/s^2)}$

$\frac{F}{W} = 4.153*10^{-8}$

Therefore the ratio is $4.153*10^{-8}$

3 0

3 years ago

Drag and drop each description into the appropriate category:

Anestetic [448]

Answer:

All of the following are already correctly categorized. This facts about these radioactive decays are true. Further, I have explained below in explanation portion.

Explanation:

Alpha Decay: Yes it cannot penetrate through paper & Yes it emits Alpha particle when an element undergoes the process of Alpha Decay. Here's how:

First of all, we need to understand why a particular element decays? why radioactive decay occurs?

It is because, everything in this universe tends to achieve its stable state. Everything put efforts to be in their stable state. Likewise, when radioactive elements like Uranium or Thorium become unstable they undergo the process of Alpha decay. As a result, they emit energy and alpha particle.

Furthermore, Alpha decay has low penetration power and it has higher mass than Beta Decay and Gamma Decay that's why it cannot travel in long distances. Hence, it cannot pass through a sheet of paper.

Beta Decay: Yes it emits electrons or positrons and Yes it can penetrate through paper but cannot penetrate through a foil. Here's how:

Till now, we are familiar that why the process of decay occurs right? in order to be stable. Like wise Beta Decay occurs and it emits beta particle and energy. The main difference between alpha decay and beta decay is that alpha particle's mass is much greater than beta particle's mass because beta particle is either a negatively charged electron or positron (a positively charged electron or anti-electron) and we know that mass electron is much smaller.

So, Beta Decay has moderate penetrate power and it's mass is much smaller that's why it can travel in longer distances and it can penetrate paper but cannot penetrate into foil.

Gamma Decay: Yes it requires thick lead shield and yes it emits photon. Here's how:

Gamma Decay is a radioactive wave, it only emits energy in form of photons and it has no mass and no charge and but it has very low wavelength but highest energy with great penetration power and that is the reason that it can penetrate paper, it can penetrate foil but it cannot penetrate thick lead shield.

Hope, this will help :)

6 0

3 years ago

Read 2 more answers