help me please

howru

9th December 2005 - 03:41 AM

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?

I already asked you this question but i want to know if i have the right answer?

.5mv^2+mgh=.5mv^2

i got 1.12 m/s without friction so if took the proportion of that of 1.86 , it would be 1.66 m/s.

then i used the kinetic energy, and got 24.8 Joules

Nessus

9th December 2005 - 03:55 AM

Potential energy difference: E = mgh = 18*9.8*2.5 = 441J
Kinetic energy at the end: E = 1/2*mv^2 = 31.1364 J
Loss in energy is then approx 410 J

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