A 120-N child is in a swing thatis attached to ropes 2.20 mlong. Find the gravit

Question

A 120-N child is in a swing thatis attached to ropes 2.20 mlong. Find the gravitational potential energy associated with thechild relative to her lowest position at the following times. (a) when the ropes are horizontal
J

(b) when the ropes make a 25.0° anglewith the vertical
J

(c) when the child is at the bottom of the circular arc
J
(a) when the ropes are horizontal
J

(b) when the ropes make a 25.0° anglewith the vertical
J

(c) when the child is at the bottom of the circular arc
J

Explanation / Answer

(A) When the string is horizontal, height h = 2.20m          equation forgravitational potential energy (P.E.): = m*g*h          N =1kg.m/s2      and      J =1kg.m2/s2          120-N = m*a => m = 12.3 kg              P.E. = (120-N)(2.20 m)              P.E. = 264 J (B) When string makes 25 degree with the vertical,thechild's height relative to lowest position 'h' =l (1 - cos 25)        'h'=2.20*( 1 - 0.906 ) = 0.206m           nowgravitational potential energy (P.E.) =m*g*h              P.E. = (120-N)(0.206 m)              P.E. = 24.7 J (C) At the bottom height is zero , hence P.E. =0

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.