Those are the two points on the map of the stars called
the "solstices" ... one in June and one in December.
Answer:
Energy
Explanation:
Waves can transfer energy over distance without moving matter the entire distance. For example, an ocean wave can travel many kilometers without the water itself moving many kilometers. The water moves up and down—a motion known as a disturbance. It is the disturbance that travels in a wave, transferring energy.
Answer:
They come from metal elements or alloys.
Explanation:
Different materials produce magnets of varying strengths. Ceramic magnets, also known as ferric magnets, are made of iron oxide in a ceramic composite. Samarium cobalt magnets are created from the combination of cobalt and samarium, which is a rare-earth element. Neodymium magnets contain boron, iron and neodymium, also a rare-earth element. The strongest naturally occurring magnet is lodestone, a form of magnetite. It attracts even small objects, such as staples and paper clips.
Answer:
, 6.1 s
Explanation:
The motion of the dropped penny is a uniformly accelerated motion, with constant acceleration
![g=5.3 ft/s^2](https://tex.z-dn.net/?f=g%3D5.3%20ft%2Fs%5E2)
towards the ground. If the penny is dropped from a height of
![h_0 = 100 ft](https://tex.z-dn.net/?f=h_0%20%3D%20100%20ft)
the vertical position of the penny at time t is given by the equation
![h(t) = h_0 - \frac{1}{2}gt^2](https://tex.z-dn.net/?f=h%28t%29%20%3D%20h_0%20-%20%5Cfrac%7B1%7D%7B2%7Dgt%5E2)
where the negative sign is due to the fact that the direction of the acceleration is downward.
We want to know the time t at which the penny reaches the ground, which means h(t)=0. Substituting into the equation, it becomes
![0=h_0 - \frac{1}{2}gt^2](https://tex.z-dn.net/?f=0%3Dh_0%20-%20%5Cfrac%7B1%7D%7B2%7Dgt%5E2)
And re-arranging it, we find an expression for the time t:
![t=\sqrt{\frac{2h_0}{g}}](https://tex.z-dn.net/?f=t%3D%5Csqrt%7B%5Cfrac%7B2h_0%7D%7Bg%7D%7D)
And substituting the numbers, we can also find the numerical value:
![t=\sqrt{\frac{2(100 ft)}{5.3 ft/s^2}}=6.1 s](https://tex.z-dn.net/?f=t%3D%5Csqrt%7B%5Cfrac%7B2%28100%20ft%29%7D%7B5.3%20ft%2Fs%5E2%7D%7D%3D6.1%20s)