Part A)
As we know that spring force is given by
F = kx
here x = stretch in the spring from natural length
So here when spring reaches to its natural length
Force due to spring = 0
so acceleration = 0
Part b)
When spring is compressed from its natural length it will have elastic potential energy in it
so it is given by

now we know that there is no friction in it so maximum kinetic energy of the launcher must be equal to the elastic potential energy of the spring

here we have
k = 70 N/m
x = 0.4 m


Part c)
Now to find the speed we know that



so its speed is 6.11 m/s
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Answer:
No.
Explanation:
- According to Faraday's law, the induced emf in the circuit is given by :
, it is proportional to the rate of change of magnetic flux.
- In this case, a short piece of wire that is not attached to anything and move it up and down in a magnetic field. It means that the circuit is not completed here. It is an open circuit. For the induction of current, a circuit must be completed.
- Hence, no current will induce.