I'm stuck on the same question, as well :(
Answer:
Energy cannot be created or destroyed.
Explanation:
its in the name, law of "conservation" of energy. energy can only change forms not be destroyed
Answer:
The work done by gravity is 
Explanation:
The data given in the question is :
Mass is 
Height from ground is 
As we know , the work done is state function , it depends on initial and final position not on the path followed.
So, work done by gravity = change in potential energy
Work done = Initial potential energy - final potential energy
Insert values from question
Work done = 
Work done = 
So, work done = 
Hence the work done by gravity is
Answer:
The momentum of bath cars is 40000 Ns which make the difficulty to stop each car in aspect of fprce is the same.
Explanation:
Momentum (P) =mass(m) × velocity (v)
For car A,
P = m × v = 1000 × 40 = 40000 Ns
For car B,
P = m × v = 4000 × 10 = 40000 Ns
Force (F) = Momentum change(ΔΡ)/ time taken(t)
F = ΔΡ/t
When stopping the car the momentum changes from 40000 Ns to 0
So momentum change in both cars is the same. So to stop the two cars in a given time (t) you need the same force, which means you will feel same difficulty.
The air flows slower in a bigger space. The air in a small space hit each other heating up, and move faster and faster. is that what your asking?
