Answer
See the detailed answer below.
Work Step by Step
a) A spring of constant $k$ is compressed 15 cm to the left and then it is released to fire a 200 g marble toward the right. The speed of the marble after it is not touching the spring anymore is 2 m/s. If you know that the marble is moving without friction, find the spring constant $k$.
b) See the graph below.
c) Solving the given equation for $k$;
$$k=\dfrac{0.2\times 2^2}{(-0.15)^2}=\color{red}{\bf 35.6}\;\rm N/m$$
