1. A 5.0000 x 10-kg subway train is brought to a stop from a speed of 0.6000 m/s in 0.3000 m by a large spring bumper at the end of its track. Neglect friction. Think & Prepare 1. Make note of what's given and what's unknown. Relate known quantities to symbols. 2. Draw a labeled sketch if possible. 3. Identify the physics principle and approach. Write down relevant equations symbolically. Simplify if possible. 4. Insert numerical quantities to solve for unknowns. 5. Does the answer make sense? (a) What external forces act on the train? Are they conservative or non-conservative? Normal force: Spring force: Weight: (b) Is mechanical energy conserved during the stopping of the train? Think about reasons for your answer. (c) What is the force constant k of the spring? k= N/m

1. A 5.0000 x 10-kg subway train is brought to a stop from a speed of 0.6000 m/s in 0.3000 m by a large spring bumper at the end of its track. Neglect friction. Think & Prepare 1. Make note of what's given and what's unknown. Relate known quantities to symbols. 2. Draw a labeled sketch if possible. 3. Identify the physics principle and approach. Write down relevant equations symbolically. Simplify if possible. 4. Insert numerical quantities to solve for unknowns. 5. Does the answer make sense? (a) What external forces act on the train? Are they conservative or non-conservative? Normal force: Spring force: Weight: (b) Is mechanical energy conserved during the stopping of the train? Think about reasons for your answer. (c) What is the force constant k of the spring? k= N/m