Question

A child with mass m = 16.6 kg slides down a slide 4.50 m high, and reaches the bottom with a speed of 1.00 m/s. How much thermal energy (in Joules) was generated in the process? Answer to two decimal places.

Answer 1

By, Energy conservation,

Initial energy (Ei) = Final energy(Ef)

Let, the energy lost when boy is coming down be released as thermal energy(T.E)(as remaining energies are negligible)

Initially boy has inly Potential energy, it is converted as Kinetic and thermal energy

Potential energy = P. E= mgh= 747J

m=mass

g= acceleration due to gravity

h = height of slide

Initial Energy=Ei= P. E= 747J ------(1)

Kinetic energy = K. E= mv²/2 =8.3J

v= speed at which boy reaches the ground

Final Energy = Ef= K.E+T.E =8.3+T.E-------(2)

Equating 1 & 2equations

747= 8.3+T.E

T. E= 738.7J

Thermal Energy released is 738.7J