Spiderman uses his spider webs to save a runaway train moving about 60 km/h. His web streches a few city blocks (500 m) before the 10^4 kg train comes to a stop. Assuming the web acts like a spring, estimate the effective spring constant in N/m.

A  2.3 kg mass  is attached to a horizontal spring of constant k = 578 N/m and pushed so that the spring compresses by 0.064 m. If the block is now released and the surface is frictionless, calculate the block's speed after it leaves the spring.

A spring attached to a mass is displaced 30 cm from its equilibrium position, At this point it has 2.0 J of potential energy. What is the spring constant, k, of the spring? O 44 Nm 3600 Nm 0.004 Nm 0.36 Nm

A small spring is laying horizontal on a table and is compressed by 0.50 m. A small mass of 0.25 kg is placed in front of the compressed spring. a) When the spring is released it accelerates the box at a = 8.0m/s . What is the value of the spring constant, k for the spring? Ignore friction for part (a). b) When the small mass loses contact with the spring it moves over a part of the table where there exists a friction force between the small mass and the table. If the box comes to a stop after sliding 5.0 m, using your knowledge of work, find the coefficient of friction between the sliding mass and the table.