1.) A 1220 kg car rolling on a horizontal surface has a speed of 50 km/hr when i

Question

1.)A 1220 kg car rolling on a horizontal surface has a speed of 50 km/hr when it strikes a horizontal coiled spring and is brought to rest in a distance of 3.5 m. What is the spring constant (in N/m) of the spring? (Ignore nonconservative forces such as friction.)

2.) A spring has a spring constant "k" of 560 N/m. How much must this spring be compressed (in meters) to store 50 J of energy?

3.) An object slides down a frictionless 33 degree incline whose vertical height is 47.0 cm. How fast is it going in meters/second when it reaches the bottom?

4.) Two railroad cars, each of mass 2800 kg and traveling 60.0 km/hr, collide head-on and come to rest. How much thermal energy in joules is produced in this collision?

Explanation / Answer

Mass of the car m = 1220 kg

Speed V = 50 km/hr

V = 50*1000/3600 m/s

V = 13.89 m/s

distance X = 3.5 m

here kinetic energy of the car will convert to potential energy of the spring

1/2 KX2 = 1/2 mV2

K (3.5)2 = (1220)(13.89)2

K = 19214 N/m

(2) K = 560 N/m U = 50 J

U = 1/2 KX2

50 = 1/2 (560)X2

X = 0.42 m

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