Answer:
Two cars of equal weight and braking ability are travelling along the same road but combined with other factors it could mean the difference between life.
250kg
would have momentum that is being caried by the impact of the trow
Answer: The force constant k is 10600 kg/s^2
Step by step:
Use the law of energy conservation. When the elevator hits the spring, it has a certain kinetic and a potential energy. When the elevator reaches the point of still stand the kinetic and potential energies have been transformed to work performed by the elevator in the form of friction (brake clamp) and loading the spring.
Let us define the vertical height axis as having two points: h=2m at the point of elevator hitting the spring, and h=0m at the point of stopping.
The total energy at the point h=2m is:
![E_{tot}=E_{kin}+E_{pot}\\E_{tot}= \frac{1}{2}mv^2+mg\Delta h = \frac{1}{2}2000 kg 4^2\frac{m^2}{s^2}+2000kg\, 9.8\frac{m}{s^2}2m=55200\,kg\frac{m^2}{s^2}](https://tex.z-dn.net/?f=E_%7Btot%7D%3DE_%7Bkin%7D%2BE_%7Bpot%7D%5C%5CE_%7Btot%7D%3D%20%5Cfrac%7B1%7D%7B2%7Dmv%5E2%2Bmg%5CDelta%20h%20%3D%20%5Cfrac%7B1%7D%7B2%7D2000%20kg%204%5E2%5Cfrac%7Bm%5E2%7D%7Bs%5E2%7D%2B2000kg%5C%2C%209.8%5Cfrac%7Bm%7D%7Bs%5E2%7D2m%3D55200%5C%2Ckg%5Cfrac%7Bm%5E2%7D%7Bs%5E2%7D)
The total energy at the point h=0m is:
![E_{tot}=E_{kin}+E_{pot}+Work=0+0+ Work\\E_{tot} =F_{friction}\Delta h+\frac{1}{2}k (\Delta h)^2=17000N\cdot 2m+\frac{1}{2}k\cdot 2^2 m^2](https://tex.z-dn.net/?f=E_%7Btot%7D%3DE_%7Bkin%7D%2BE_%7Bpot%7D%2BWork%3D0%2B0%2B%20Work%5C%5CE_%7Btot%7D%20%3DF_%7Bfriction%7D%5CDelta%20h%2B%5Cfrac%7B1%7D%7B2%7Dk%20%28%5CDelta%20h%29%5E2%3D17000N%5Ccdot%202m%2B%5Cfrac%7B1%7D%7B2%7Dk%5Ccdot%202%5E2%20m%5E2)
The two Energy values are to be equal (by law of energy conservation), which allows us to determine the only unknown, namely the force constant k:
![17000N\cdot 2m+\frac{1}{2}k\cdot 2^2 m^2 = 55200 \,kg\frac{m^2}{s^2}\\k = \frac{55200-34000}{2}\,\frac{kg}{s^2}=10600\frac{kg}{s^2}](https://tex.z-dn.net/?f=17000N%5Ccdot%202m%2B%5Cfrac%7B1%7D%7B2%7Dk%5Ccdot%202%5E2%20m%5E2%20%3D%2055200%20%5C%2Ckg%5Cfrac%7Bm%5E2%7D%7Bs%5E2%7D%5C%5Ck%20%3D%20%5Cfrac%7B55200-34000%7D%7B2%7D%5C%2C%5Cfrac%7Bkg%7D%7Bs%5E2%7D%3D10600%5Cfrac%7Bkg%7D%7Bs%5E2%7D)
It's velocity is not constant as direction is changing.
We know, velocity is speed with direction, so if direction is changing, velocity can't be constant, doesn't matter that speed is constant.
Hope this helps!
B. gas has no definite shape or volume. liquid has definite volume but no definite shape