So you can have a understanding of what you are doing and figure out your overall goal
Answer:
<em>765,000Joules or 765kJ</em>
Explanation:
The Quantity of heat required is expressed as;
Q = (mcΔt)al + (mcΔt)water
m is the mass
c is specific heat capacity
Δt is the change in temperature
Q = (3(900)(90-5)) + (1.5(4200)(90-5))
Q = 2700*85 + 6300*85
Q = (2700+6300)85
Q = 9000*85
<em>Q = 765,000</em>
<em>Hence the amount of energy needed is 765,000Joules or 765kJ</em>
A compass works the way it does because Earth has a magnetic field that looks a lot like the one in a magnet. The Earth's field is completely invisible, but it can be felt by a compass needle on the Earth's surface, and it reaches thousands of miles out into space.
Double
Explanation:
Since the period T of a pendulum is given by
![T = 2\pi \sqrt{\dfrac{l}{g}}](https://tex.z-dn.net/?f=T%20%3D%202%5Cpi%20%5Csqrt%7B%5Cdfrac%7Bl%7D%7Bg%7D%7D)
By increasing the length of the pendulum by 4, the period becomes
![T' = 2\pi \sqrt{\dfrac{4l}{g}} = 2\left(2\pi \sqrt{\dfrac{l}{g}}\right) = 2T](https://tex.z-dn.net/?f=T%27%20%3D%202%5Cpi%20%5Csqrt%7B%5Cdfrac%7B4l%7D%7Bg%7D%7D%20%3D%202%5Cleft%282%5Cpi%20%5Csqrt%7B%5Cdfrac%7Bl%7D%7Bg%7D%7D%5Cright%29%20%3D%202T)
You can see that the period doubles when we increase the length by a factor of 4.
Because the tip of the moon's shadow ... the area of "totality" ... is never more than a couple hundred miles across, It never covers a single place for more than 7 minutes, and can never stay on the Earth's surface for more than a few hours altogether during one eclipse.
If you're not inside that small area, you don't see a total eclipse.