Learn what kinetic energy means and how it relates to work.
Log in Bhoovesh Waran 8 years agoPosted 8 years ago. Direct link to Bhoovesh Waran's post “in the exercise 2 , how i...” in the exercise 2 , how is the total chemical potential energy stored in the propellant is (Energy density) x (mass of hydrazine)?? • (10 votes) vinnv226 8 years agoPosted 8 years ago. Direct link to vinnv226's post “By definition, "energy de...” By definition, "energy density" tells you energy per mass for the propellant. In other words, energy density is equal to the amount of energy contained in each kilogram of propellant. Multiplying by the number of kilograms of propellant will thus give you the total energy. (32 votes) WAJIH RIZVI 8 years agoPosted 8 years ago. Direct link to WAJIH RIZVI's post “I don't understand what n...” I don't understand what net work means. It says in the article that kinetic energy can be equal to the net work done on a system. What does net work mean? • (10 votes) Ishaan Sahasrabudhe 5 years agoPosted 5 years ago. Direct link to Ishaan Sahasrabudhe's post “Net-work just means the _...” Net-work just means the total work done by the system. And the value of net work = change in kinetic energy. (22 votes) 😊 8 years agoPosted 8 years ago. Direct link to 😊's post “prove that K.E = 1/2 mv2?” prove that K.E = 1/2 mv2? • (5 votes) 🚀The knowledge Hunter🔭 8 years agoPosted 8 years ago. Direct link to 🚀The knowledge Hunter🔭's post “You are asking a question...” You are asking a question, which is answered very well in the current topic :( However, here is somewhat a different proof based on the same idea, although I tried to increase the understanding. Hope this helps. (21 votes) Kyle Delaney 8 years agoPosted 8 years ago. Direct link to Kyle Delaney's post “Why is kinetic energy rel...” Why is kinetic energy related to the square of the velocity, as opposed to momentum which varies linearly with velocity? How do I know when I'm dealing with a momentum problem or a kinetic energy problem? • (8 votes) blancaroca60 7 years agoPosted 7 years ago. Direct link to blancaroca60's post “The simplest derivation i...” The simplest derivation is this..... Work W=Fx sort of definition. (5 votes) jacobkwak9293 4 years agoPosted 4 years ago. Direct link to jacobkwak9293's post “For exercise 2, I want to...” For exercise 2, I want to know the units of factors used in the last step to calculate the V value. When I calculated the velocity with Ed = 1.6MJ/kg, Mp = 1000kg, and Mr = 100kg, I got 5.657. It looks like 1000 was multiplied to the value, but why? Is it because of the MJ to J? But isn't 1megajoule = 1000000J? • (6 votes) Ahmad Abu Zainab 4 years agoPosted 4 years ago. Direct link to Ahmad Abu Zainab's post “Yes, you should convert M...” Yes, you should convert MJ to J. The reason that your answer must me multiplied by 1000 since sqrt(10^6)=10^3=1000 (4 votes) GiGI25 4 years agoPosted 4 years ago. Direct link to GiGI25's post “if there is the another w...” if there is the another way to say kinetic energy • (7 votes) ▫◻Cadence◻▫ a year agoPosted a year ago. Direct link to ▫◻Cadence◻▫'s post “There are multiple, but k...” There are multiple, but kinetic energy is the most appropriate term :) (1 vote) muhammad 5 years agoPosted 5 years ago. Direct link to muhammad's post “if the propellant is cont...” if the propellant is contained by rocket then the K.E of rocket shouldn't be => K.E= 0.5(mr+mp)(v)^2 • (4 votes) Andrew M 5 years agoPosted 5 years ago. Direct link to Andrew M's post “The propellant is used up...” The propellant is used up as the rocket gains speed, right? When the propellant is all gone, the rocket's KE has to be equal to whatever energy was produced by the propellant as it burned (actually the propellant leaves as gas and that gas has KE, too, so it' really the sum of that KE plus the KE of the rocket that has to add up) (6 votes) Thermos 7 years agoPosted 7 years ago. Direct link to Thermos's post “Can you say that kinetic ...” Can you say that kinetic energy is the source of sound energy? Can you say that kinetic energy and sound energy exist together? • (5 votes) Darth Skytron 5 years agoPosted 5 years ago. Direct link to Darth Skytron's post “Sound energy is a type of...” Sound energy is a type of kinetic energy. (3 votes) Ada Li 5 years agoPosted 5 years ago. Direct link to Ada Li's post “Why does motion need ener...” Why does motion need energy? • (4 votes) gagste001 a year agoPosted a year ago. Direct link to gagste001's post “there would be no motion ...” there would be no motion with out energy (1 vote) Jay Malave 7 years agoPosted 7 years ago. Direct link to Jay Malave's post “If you see in first parag...” If you see in first paragraph,how will object move with a constant speed if I apply • (1 vote) Andrew M 7 years agoPosted 7 years ago. Direct link to Andrew M's post “If it stops, that means s...” If it stops, that means someone or something else was "applying energy". In physics we call that "doing work". Friction does work to stop the object after you did work to get it moving. If you did it in outer space the object wouldn't stop (6 votes)Want to join the conversation?
To prove that Kinetic Energy is ½ mv^2
We already know that Energy w = f x s that is force x displacement.
So, ΔK = W = FΔs = maΔs
From the third equation of motion that is v^2 - u^2 = 2aΔs (-1)
where v = final velocity, u = initial velocity, a = acceleration, and Δs denotes change in displacement
ΔK = maΔs, so from equation (1) ΔK = m(v^2 - u^2) / 2
=> ½ mv^2 - ½ mu^2
but If kinetic energy is the energy of motion then, naturally, the kinetic energy of an object at rest should be zero. Therefore, we don't need the second term and an object's kinetic energy is just½ mv^2
Then putting F=ma and x=(1/2)at^2 in above gives
W=(1/2)m(a^2)(t^2)
=(1/2)m v^2
This is called the kinetic energy, KE.
If you realise it doesn't matter how one arrives at the given speed v then this result must be quite general.
i know it's incorrect but can't figure out .... please clarify , its confusing me
plus , how can the K.E of rocket equal to the CHEM P.E of hydrazine?
energy only once? It will stop after a certain interval of time
