Question

Mountaineers often use a rope to lower themselves down the face of a cliff (this is called rappelling). They do this with their body nearly horizontal and their feet pushing against the cliff (Figure 1). Suppose that an 81.9-kgkg climber, who is 1.83 mm tall and has a center of gravity 1.0 mm from his feet, rappels down a vertical cliff with his body raised 29.6 ∘∘ above the horizontal. He holds the rope 1.45 mm from his feet, and it makes a 29.1 ∘∘ angle with the cliff face.

1.What tension does his rope need to support?

Express your answer using two significant figures.

2Find the horizontal component of the force that the cliff face exerts on the climber's feet.

Express your answer using two significant figures.

Answer 1

The height of the climber h = 1.83 m

The mass of the climber M = 81.9 kg

Centre of gravity = 1.0 m

(1)

Let the man is the object. So he has 3 forces acting on him (i) Tension, T at A = 24.2 from vertical, (ii) gravity straight down (mg), acting at his center of gravity and (iii) wall pushing out Fn.

(2)

The horizontal component of the force that the cliff face exerts on the climber's feet is x=normal force (n)