Answer:
(a) 2569.56 J
(b) 821.566 J
Explanation:
(a)When the performer slides down from 3.8m high its potential energy is converted to kinetic energy.
[tex]E_k = E_p[/tex]
[tex]E_k = mgh[/tex]
where m = 69 kg is the her mass and h = 3.8 mis the vertical distance she traveled, g = 9.8m/s2 is the constant gravitational acceleration.
[tex]E_k = 69*9.8*3.8 = 2569.56 J[/tex]
(b) If friction applies an F = 460N force on her, over 3.8m this force would have done a work of:
[tex]W_f = F * h = 460 * 3.8 = 1748 J[/tex]
Some of the potential energy will be lost to this work, so the remaining kinetic energy of her is
[tex]E_k = E_p - W = 2569.56 - 1748 = 821.56 J[/tex]
