“to predict the speed that a coaster will reach before it is ever placed on the track. ... When coaster goes up by height h then its gravitational potential energy increases by the amount m.g.h where m = mass of coaster, h = height of coaster and g = gravitational acceleration due to Earth”
i think so it is frequency
Answers:
a) 
b) 
c) 
Explanation:
We have the following data:
is the spring constant
is the amplitude of oscillation
is the velocity of the block when
Now let's begin with the answers:
<h3>a) Mass of the block</h3>
We can solve this by the conservation of energy principle:
(1)
Where:
is the initial potential energy
is the initial kinetic energy
is the final potential energy
is the final kinetic energy
Then:
(2)
Isolating
:
(3)
(4)
(5)
<h3>b) Period</h3>
The period
is given by:
(6)
Substituting (5) in (6):
(7)
(8)
<h3>c) Maximum acceleration</h3>
The maximum acceleration
is when the force is maximum
, as well :
(9)
Being 
Hence:
(10)
Finding
:
(11)
(12)
Finally:

Hmm doesnt soujd familiar
The correct answer is - D. 1 percent.
The United States are the biggest consumer of electricity in the world. Because of that the United States are using multiple different sources in order to satisfy the demand for the electricity. The solar energy though accounts for only 1% of the total amount of produced electricity in the country and that is concerning. The biggest concern of course is the environmental one as the majority of the electricity is produced by sources that are polluting the environment. The other concern is that the United States are not using their potential in gaining more electricity from the solar radiation when taken in account that they have very large areas in the country that have a lot of intense solar radiation and clear skies throughout most of the year.