Question 1186163: A 25 kg child sits in a swing that is attached to ropes 1.6 m long. Find the potential energy of the child relative to his lowest position when the ropes (a) are horizontal, (b) are vertical, and (c) make 30° with the horizontal
Answer by ikleyn(52752)   (Show Source):
You can put this solution on YOUR website! .
A 25 kg child sits in a swing that is attached to ropes 1.6 m long.
Find the potential energy of the child relative to his lowest position when the ropes
(a) are horizontal,
(b) are vertical, and
(c) make 30° with the horizontal
~~~~~~~~~~~~~~
The potential energy relative to the lowest position is the product
P = mgh,
where m is the mass, g is the gravity acceleration, h is the level relative to the lowest position.
You are given m = 25 kg; for the gravity acceleration take g = 10 m/s^2.
(a) In position (a), the relative level is 1.6 m (obviously), so the potential energy is
P = 25*10*1.6 = 400 joules. ANSWER
(b) In position (b), the relative level is 0 m (obviously), so the potential energy is
P = 25*10*0 = 0 joules. ANSWER
(c) In position (c), the relative level is 0.8 m (obviously: you have 30°-60°-90° triangle), so the potential energy is
P = 25*10*0.8 = 200 joules. ANSWER
( In position (c), I assume - naturally - that the rope is 30° below horizontal)
Solved. All questions are answered.
|
|
|
