Physics
posted by Aaron .
A daredevil attempts to swing from the roof of a 24m high bulding to the bottom of an identical building using a 24m rope. He starts from rest with the rope horizontal, but the rope will break if the tension force in it is twice the weight of the daredevil. How high is the rope above level when it breaks? (Hint: Apply the law of conservarion of energy) Also, the building are 24m apart.
I don't understand; how can I do this without knowing the daredevil's weight?

please I really need help with this

The falling distance as a function of angle is f = 24 cos A
where A is the angle between the line and the wall of the target building. It starts out at A = 90 and if he got there, ends at A = 0
The component of the weight along the line is m g cos A
(1/2) m v^2 = m g f = m g (24 cos A)
so
v^2 = 48 g cos A
The centripetal acceleration is
v^2/r = 2 g cos A
The tension in the line at breaking = 2 m g + m g cos A which is the mass times the centripetal acceleration
T  m g cos A = 2 m g cos A
T = 3 m g cos A
so when T = 2 m g
2 m g = 3 m g cos A
cos A = 2/3
A = 48.2 deg
distance fallen = 24 cos 48.8
= 24(2/3) = 16
an 24  16 = 8 above ground
cos A = 1
A = 0
That is right at the ground. 
wow, that was more elaborate than I thought it would be. Thank you so much for answering my qustion. :]

These were just to keep my geometry in mind.
cos A = 1
A = 0
That is right at the ground.
Respond to this Question
Similar Questions

Physics
An object is swinging from a point that is horizontal compared to the lowest point the object will reach (where the rope is vertical). If the length of the rope is 2 meters and the mass of the object is 30 kg, what is the tension in … 
physics
A stunt man whose mass is 70 kg swings from the end of a 4.4 m long rope along the arc of a vertical circle. Assuming that he starts from rest when the rope is horizontal, find the tensions in the rope that are required to make him … 
ap Physics
AP PROBLEM CHILD ON A SWING AN ADULT EXERTS A HORIZONTAL FORCE ON A SWING THAT IS SUSPENDED BY A ROPE OF LENGTH L, HOLDING IT AN AN ANGLE q WITH THE VERTICAL. THE CHILD IN THE WING HAS WEIGHT W AND DIMENSIONS THAT ARE NEGLIGIBLE COMPARED … 
physics
A swinging rope is used to transport 0.03kg of medicine. The rope has a length of 2.4m, so that the tension of the rope at the bottom point of the swing is 0.3929N. What is the tangential speed of the medicine at this bottom point? 
HELPphysics
Walking by a pond, you find a rope attached to a tree limb 5.1 m off the ground. You decide to use the rope to swing out over the pond. The rope is a bit frayed but supports your weight. You estimate that the rope might break if the … 
Physics
A child swings from a rope of length L. If she starts her swing with the rope horizontal what is her acceleration at the bottom of the swing? 
Physics
A rope is attached from a truck to a 1403 kg car. The rope will break if the tension is greater than 2375 N. Neglecting friction, what is the maximum possible acceleration of the truck if the rope does not break? 
physics
An adventurous archaeologist crosses between two rock cliffs by slowly going hand over hand along a rope stretched between the cliffs. He stops to rest at the middle of the rope. The rope will break if the tension in it exceeds 25000N, … 
Physics
A tightrope walker wonders if her rope is safe. Her mass is 60 kg and the length of the rope is about 20 m. The rope will break if its tension exceeds 7500 N. What is the smallest angle at which the rope can bend up from the horizontal … 
Physics
A rope kept on a horizontal plane moves with a constant acceleration. If a constant force "f" acts on the rope,the tension of the middle of the rope is T. Which of the following are true?