Physics, 02.11.2019 19:31 joeljuarez128oyusun

A6 kg block initially at rest is pulled to east along a horizontal, frictionless surface by a constant horizontal force of 12 n. find the speed of the block after it has moved 3m.

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Answer from: austinwilliams60

Answers:

a) 3.46 m/s

b) $2 m/s^{2}$

Explanation:

The complete question is written below:

A 6 kg block initially at rest is pulled to East along a horizontal, frictionless surface by a constant horizontal force of 12 N.

a) Find the speed of the block (using work-kinetic energy theorem) after it has moved 3.0 m.

b) Find the acceleration of the block using Newton.

a) Speed of the block after it has moved 3m

Let's begin by explaining the following:

The Work done by a Force refers to the release of potential energy from a body that is moved by the application of that force to overcome a resistance along a path. In addition, is a scalar quantity, and its unit in the International System of Units is the Joule (like energy).

Now, when the applied force is constant and the direction of the force and the direction of motion are parallel, the equation to calculate it is:

W=F.d (1)

Where:

F= 12 N is the force exerted to pull the block to the East

d= 3 m is the distance the block has been moved

W=(12 N)(3 m) (2)

W=36 Nm= 36 J (3)

On the other hand, energy is the ability of matter to produce work in the form of movement, light, heat, among others. In this sense, according to the Work-Kinetic Energy Theorem we have:

$W=\Delta K=K_{f}-K_{o}$ (4)

Where:

$\Delta K$ is the variation in kinetic energy which is equal to:

$K=\frac{1}{2}mV^{2}$ (5)

Where:

m=6kg is the mass of the block

is the velocity

Hence, the Work-Kinetic Energy Theorem is written as follows:

$W=\frac{1}{2}mV_{f}^{2} - \frac{1}{2}mV_{o}^{2}$ (6)

Where the initial velocity is zero ( $V_{o}=0 m/s$ ) since we are told the block is initially at rest:

$W=\frac{1}{2}mV_{f}^{2}$ (7)

So, we have to find the final velocity $V_{f}$ , substituting (3) in (7):

$36 J=\frac{1}{2}6 kg V_{f}^{2}$ (8)

$V_{f}=3.46 m/s$ (9) This is the speed of the block after it has moved 3m

b) Acceleration of the block

According to Newton's second law of motion, which relates the force with the mass and the acceleration of an object, we have:

F=m.a (10)

On the other hand, acceleration is the variation of velocity $\Delta V$ in time $\Delta t$ :

$a=\frac{\Delta V}{\Delta t}$ (11)

Then, equation (10) is rewritten as:

$F=m \frac{\Delta V}{\Delta t}$ (12)

Isolating $\Delta t$ :

$\Delta t=\frac{m \Delta V}{F}$ (13)

Since $\Delta V=V_{f}-V_{o}$ and $V_{o}=0$ , we have:

$\Delta V=V_{f}=3.46 m/s$

$\Delta t=\frac{(6 kg) (3.46 m/s)}{12 N}$ (14)

$\Delta t=1.73 s$ (15)

Substituting (15) in (11):

$a=\frac{3.46 m/s}{1.73 s}$ (16)

Finally:

$a=1.99 m/s^{2} \approx 2 m/s^{2}$ This is the acceleration

Answer from: Quest

quantum mechanics or quantum physics is physics of very small objects (particles) and physical entities.

quantum physics has some parallels to our macro world and some pretty unique ideas which theoretically and mathematically proven to be true even though we will never be able to access them because of our size.

there are many types of particles: subatomic, elementary etc.

subatomic means they are smaller than atom, elementary means they are at the very basis of everything.

subatomic particles are for eg. protons, neutrons but not electrons.

elementary particles are categorised into 3 groups by what they do.

these 3 groups are quarks, leptons and bosons.

light for example is a particle more precisely a photon a part of leptons.

proton (subatomic particle) is made out of 2 up quarks and 1 down quark each of these has a fractional charge like $\frac{1}{3}$ . (i crazy)

most famous scientist who contributed to this physics are:

max planckalbert einsteinerwin schrödingermany

the topic itself us understand a lot and will probably be vastly used in the future (quantum computers, understanding the big bang,

we also must not forget quantum effects like:

superposition (where 1 thing can be this and that at the same time),entanglement (where two particles are seemingly connected by some sort of unknown (or known) force, energy, matter (i know all that can be the same at least it was at the beginning)

and there is more. but probably too much for this answer to be consistent due to my average understanding of this topic.

hope this you understand quantum mechanics a little more. i'm not an expert in the topic (so don't be like wth if you are an expert) but i'm very interested in it.

anyways quantum physics is a very hard topic (harder than physics (perhaps)) therefore searching for every information there is about it and learning it is unfortunately impossible (you can only specialise into 1 - 3 things or more (perhaps

have fun and i wish you luck!

r3t40

Answer from: Quest

weather forecasts are done by collecting data about the current state of the atmosphere mainly the temperature, humidity and wind and using meteorology, to determine the atmosphere that evolves over time. the h and l mean the high and low pressure. the red strip is a warm front. the blue strip is a cold front. the blue and red strip is a stationary front. the purple strip is a occluded front.

explanation:

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