Answer: 0.192 N/m
Explanation:
Well, generally when a Hooke's Law experiment is performed the plot is in fact Force vs Displacement, being the Force (in units of Newtons) in the Y-axis and the Displacement (in units of meters) in the X-axis.
In addition, if we add a linear fit the resultant equation will be the Line equation of the form:
Where 
is the slope and 
is the point where the line intersects the Y-axis.
So, if the equation is:
The slope of this line is 
which is also the spring constant 
.
Answer:
35.14°C
Explanation:
The equation for linear thermal expansion is 
, which means that a bar of length 
with a thermal expansion coefficient 
under a temperature variation 
will experiment a length variation 
.
We have then = 0.481 foot, = 1671 feet and = 0.000013 per centigrade degree (this is just the linear thermal expansion of steel that you must find in a table), which means from the equation for linear thermal expansion that we have a 
= 22.14°. As said before, these degrees are centigrades (Celsius or Kelvin, it does not matter since it is only a variation), and the foot units cancel on the equation, showing no further conversion was needed.
Since our temperature on a cool spring day was 13.0°C, our new temperature must be 
= 35.14°C
The answer is A). Moving from A to C the temperature and the kinetic energy increases.
