Answer:
a)
, b) 
Explanation:
a) The system ice cube-spring is modelled by means of the Principle of Energy Conservation. Let assume that height at the bottom is zero:





b) The distance travelled by the ice cube is:


Answer:
Explanation:
The correct answer is option C.
When the battery is operating a remote control toy the energy is converted from potential energy to the kinetic energy.
A battery stores electrical potential from the chemical reaction.
When the circuit is connected to the potential energy of the battery helps in the movement of the toy.
The energy produced by the movement of the control toy is kinetic energy.
Hence, we can say that Potential energy is changed to kinetic energy
We can solve the problem by requiring the equilibrium of the forces and the equilibrium of torques.
1) Equilibrium of forces:

where

is the weight of the person

is the weight of the scaffold
Re-arranging, we can write the equation as

(1)
2) Equilibrium of torques:

where 3 m and 2 m are the distances of the forces from the center of mass of the scaffold.
Using

and replacing T1 with (1), we find

from which we find

And then, substituting T2 into (1), we find
C- 10ft. Hope this helped. Have a great day! :D