1- A 3.00 10⁵ kg subway train is brought to a stop from a speed of 0.500 m/s in 0.700 m by a large spring bumper at the end of its track. What is the force constant k of the spring (in N/m)? (Enter a number.)

N/m

2- You have a light spring which obeys Hooke's law. This spring stretches 2.46 cm vertically when a 2.20 kg object is suspended from it. Determine the following.

(a) the force constant of the spring (in N/m)

N/m

(b) the distance (in cm) the spring stretches if you replace the 2.20 kg object with a 1.10 kg object

cm

(c) the amount of work (in J) an external agent must do to stretch the spring 9.30 cm from its unstretched position

J