Answer:
![s=vt-\frac{1}{2}gt^2](https://tex.z-dn.net/?f=s%3Dvt-%5Cfrac%7B1%7D%7B2%7Dgt%5E2)
Explanation:
We could use the following suvat equation:
![s=vt-\frac{1}{2}gt^2](https://tex.z-dn.net/?f=s%3Dvt-%5Cfrac%7B1%7D%7B2%7Dgt%5E2)
where
s is the vertical displacement of the coin
v is its final velocity, when it hits the water
t is the time
g is the acceleration of gravity
Taking upward as positive direction, in this problem we have:
s = -1.2 m
![g=-9.8 m/s^2](https://tex.z-dn.net/?f=g%3D-9.8%20m%2Fs%5E2)
And the coin reaches the water when
t = 1.3 s
Substituting these data, we can find v:
![v=\frac{s}{t}+\frac{1}{2}gt=-\frac{1.2}{1.3}+\frac{1}{2}(-9.8)(1.3)=-7.3 m/s](https://tex.z-dn.net/?f=v%3D%5Cfrac%7Bs%7D%7Bt%7D%2B%5Cfrac%7B1%7D%7B2%7Dgt%3D-%5Cfrac%7B1.2%7D%7B1.3%7D%2B%5Cfrac%7B1%7D%7B2%7D%28-9.8%29%281.3%29%3D-7.3%20m%2Fs)
where the negative sign means the direction is downward.
Answer:
c. selenium
Explanation:
sulfur and selenium are in the same group
An object that has kinetic energy must be <em>moving</em>.
The formula for an object's kinetic energy is
KE = (1/2) · (the object's mass) · <u><em>(the object's speed)²</em></u>
As you can see from the formula, if the object has no speed, then its kinetic energy is zero. That's why kinetic energy is usually called the "energy of motion", and if an object HAS kinetic energy, then that tells you right away that it must be moving.
Answer: The Earth and you are attracted to the centers of each other by a pair of equal gravitational forces. The size of the force attracting you toward the center of the Earth is your "weight" on Earth. The size of the force attracting the Earth toward the center of you is the Earth's "weight" on you.
Explanation: