urgent help now please now!

howru

8th December 2005 - 01:15 AM

Two railroad cars, each of mass 6400 kg and traveling 96 km/h, collide head-on and come to rest. How much thermal energy is produced in this collision?

2) A 18 kg child descends a slide 2.50 m high and reaches the bottom with a speed of 1.86 m/s. How much thermal energy due to friction was generated in this process?

Moseley

8th December 2005 - 08:34 PM

Hi again, you are keeping us busy.
In this case we are looking to evaluate how much kinetic energy has been lost (and by implication turned into heat). 1/2*mv^2 is the KE of each and 96km/h is less metres/second.

Second part you may need to work out the speed the child would be going if frictionless system and then see what proportion 1.86m/s is of that.

Good luck.

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