Answer:
This is because these metals are used for minting (making) coins.
We are given that,

We need to find
when 
The equation that relates x and
can be written as,


Differentiating each side with respect to t, we get,



Replacing the value of the velocity


The value of
could be found if we know the length of the beam. With this value the equation can be approximated to the relationship between the sides of the triangle that is being formed in order to obtain the numerical value. If this relation is known for the value of x = 6ft, the mathematical relation is obtained. I will add a numerical example (although the answer would end in the previous point) If the length of the beam was 10, then we would have to



Search light is rotating at a rate of 0.96rad/s
Answer:
19.08 m/s
Explanation:
f = actual frequency emitted by the parked car's horn = 440 Hz
V = speed of sound = 342 m/s
f' = frequency of the horn observed by you = 466 Hz
v = speed of your car moving towards the parked car = ?
frequency of the horn observed by you is given as


v = 19.08 m/s
First of all, looks like your teacher is indeed pretty horrible. Secondly, the constraints to consider would be proper weight distribution, methods to minimize excessive motion of the building structure, and quantities such as volume and density, which would help in determining the optimal structure. Keeping the frequency of oscillation for a building low in case of an earthquake or natural disaster would also be a priority.
The total energy equation would be Kinetic energy+Potential energy