A 19.6 kg child descends a slide 3.80 m high and reaches the bottom with a speed of 2.52 m/s. How much thermal energy due to friction was generated in this process?
What formulas are used for this? How would you solve this problem?
2006-11-01 07:07:29 · 1 answers · asked by Isabel G 1 in Science & Mathematics ➔ Physics
In most physics homework problems, energy is conserved, and the following is true:
Eo = Ef
However, in this problem, energy is lost due to friction. Therefore...:
Eo - Q = Ef
We know that the child had potential energy at the top, and kinetic energy at the bottom. Use this information to calculate the energy lost due to friction. The energy lost due to friction will be denoted "Q" (Q usually stands for heat, which IS thermal energy):
Eo - Q = Ef
Rearrange the expression, since we're solving for F:
Q = Eo - Ef
Now plug in the formulas for potential and kinetic energy:
Q = mgh - (1/2)mv²
You don't have to do this, but I factored out the "m" (mass):
Q = m[gh - (1/2)v²]
You can plug things in now, since the values are all given:
Q = 19.6[(9.80)(3.80) - (1/2)(2.52)²]
Q = 668 J
2006-11-01 07:36:32 · answer #1 · answered by عبد الله (ドラゴン) 5 · 1⤊ 0⤋