In fig. 8-42, a block of mass m = 12 kg is released from rest on a frictionless incline of angle θ = 30°. below the block is a spring that can be compressed 2.0 cm by a force of 270 n. the block momentarily stops when it compresses the spring by 5.5 cm. (a) how far does the block move down the incline from its rest position to this stopping point? (b) what is the speed of the block just as it touches the spring?

a) The block moves down a distance of 35 cm down the incline from its rest position to this stopping point

b)  The speed of the block just as it touches the spring is 1.7 m/s

Explanation:

First let us determine the spring constant

Given: and

⇒

Let the distance the block moves down the incline from its rest position to this stopping point be L measured along the incline

and height of the block be H from the stopping point

a)Given that ° and where x is the distance by which the spring compresses

⇒

and using law of conservation of energy:

Energy at rest point=Energy at stopping point

⇒

⇒

Therefore,

⇒

Therefore the block moves down a distance of 35 cm down the incline from its rest position to this stopping point

b) where is the compression in spring and is the distance between starting of spring to the block

∴

Let h be the height of the block from the starting of spring

∴

using law of conservation of energy:

Energy at rest point=Energy at starting point of the spring

⇒ where is the speed of the block

⇒

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 . (i crazy)

most famous scientist who contributed to this physics are:

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:

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