Answer:
A physical change is an ice cube melting into water. The property is melting point. Another is a banana changing from yellow to brown and the property is color. A chemical change example is a pot or a tool rusting and turning from silver to a reddish-brown. It is also a color change, but it is different because the color changed chemically and not just by looks.
Answer:Explanation:
A microscopic hair examination can also determine if a hair was forcibly removed, artificially treated or diseased. A comparison microscope can be used to compare a questioned hair to a known hair sample in order to determine if the hairs are similar and if they could have come from a common source.
There are missing data in the text of the problem (found them on internet):
- speed of the car at the top of the hill:
![v=15 m/s](https://tex.z-dn.net/?f=v%3D15%20m%2Fs)
- radius of the hill:
![r=100 m](https://tex.z-dn.net/?f=r%3D100%20m)
Solution:
(a) The car is moving by circular motion. There are two forces acting on the car: the weight of the car
![W=mg](https://tex.z-dn.net/?f=W%3Dmg)
(downwards) and the normal force N exerted by the road (upwards). The resultant of these two forces is equal to the centripetal force,
![m \frac{v^2}{r}](https://tex.z-dn.net/?f=m%20%5Cfrac%7Bv%5E2%7D%7Br%7D%20)
, so we can write:
![mg-N=m \frac{v^2}{r}](https://tex.z-dn.net/?f=mg-N%3Dm%20%5Cfrac%7Bv%5E2%7D%7Br%7D%20)
(1)
By rearranging the equation and substituting the numbers, we find N:
![N=mg-m \frac{v^2}{r}=(975 kg)(9.81 m/s^2)-(975 kg) \frac{(15 m/s)^2}{100 m}=7371 N](https://tex.z-dn.net/?f=N%3Dmg-m%20%5Cfrac%7Bv%5E2%7D%7Br%7D%3D%28975%20kg%29%289.81%20m%2Fs%5E2%29-%28975%20kg%29%20%5Cfrac%7B%2815%20m%2Fs%29%5E2%7D%7B100%20m%7D%3D7371%20N%20%20)
(b) The problem is exactly identical to step (a), but this time we have to use the mass of the driver instead of the mass of the car. Therefore, we find:
![N=mg-m \frac{v^2}{r}=(62 kg)(9.81 m/s^2)-(62 kg) \frac{(15 m/s)^2}{100 m}=469 N](https://tex.z-dn.net/?f=N%3Dmg-m%20%5Cfrac%7Bv%5E2%7D%7Br%7D%3D%2862%20kg%29%289.81%20m%2Fs%5E2%29-%2862%20kg%29%20%5Cfrac%7B%2815%20m%2Fs%29%5E2%7D%7B100%20m%7D%3D469%20N%20)
(c) To find the car speed at which the normal force is zero, we can just require N=0 in eq.(1). and the equation becomes:
![mg=m \frac{v^2}{r}](https://tex.z-dn.net/?f=mg%3Dm%20%5Cfrac%7Bv%5E2%7D%7Br%7D%20)
from which we find
Answer:
the responding variable is the water boiling
Explanation:
a responding variable is the same thing as a dependent variable and an independent variable you change the independent variable is the amount of salt, the control group is how long water takes to boil without adding salt, and a constant is the same amount of water
A "variable" is a person, object, or some other well-defined item upon which a treatment is applied.
A variable is basically what you do your tests on whenever you need to test something