# physics

posted by .

The 49 kg climber is supported in the "chimney" by the friction forces exerted on his shoes and back. The climber has reduced push to verge of slip. The static coefficients of friction between his shoes and the wall, and between his back and the wall, are 1.2 and 0.8, respectively. What is the magnitude of the push he must exert? What fraction of the climbers weight is supported by the frictional force on his shoes?

• physics -

Well, if he is at the point of slip, then force friction shoes=X*mg
where x is some fraction of weight.
This means force normal=K, and mu*K= Xmg

Now if K is the normal force, then K must be acting on the back, so friction on the back is .8*mg*(1-x)

we know the two frictions have to equal weight,

.8(mg)(1-x)+1.2*X*mg=mg
.8-.8x+ 1.2x=1
.4x=.2
x= .5
so half his weight is supported by his shoes.

• physics -

force of push = (mg)/(u1+u2), so
(49*9.8)/(1.2+.8)=240.1N

fraction of weight= (u1)/(u1+u2),so
(1.2)/(1.2+.8)=.6

## Similar Questions

1. ### Physics

The 60 kg climber in Fig. 4-52 is supported in the "chimney" by the friction forces exerted on his shoes and back. The static coefficients of friction between his shoes and the wall, and between his back and the wall, are 0.82 and …
2. ### Physics

The 60 kg climber in Fig. 4-52 is supported in the "chimney" by the friction forces exerted on his shoes and back. The static coefficients of friction between his shoes and the wall, and between his back and the wall, are 0.82 and …
3. ### physics

A 70.0 kg climber is supported in the "chimney" by the friction forces exerted on his shoes and back. The static coefficients of friction between his shoes and the wall, and between his back and the wall, are 0.760 and 0.610, respectively. …
4. ### Physics

A 56 kg rock climber is climbing a "chimney" between two rock slabs as shown in the figure. The static coefficient of friction between her shoes and the rock is 1.02; between her back and the rock it is 0.70. She has reduced her push …
5. ### physics

a climber with a weight of 441 N is held by a belay rope connected to her climbing harness and belay device; the force of the rope on her has a line of action through her center of mass. The indicated angles are θ = 45˚ and …
6. ### physics

In Fig. 12-39, a climber with a weight of 441 N is held by a belay rope connected to her climbing harness and belay device; the force of the rope on her has a line of action through her center of mass. The indicated angles are θ …
7. ### Physics help.

The 78.0 kg climber is supported in the "chimney" by the friction forces exerted on his shoes and back. The static coefficients of friction between his shoes and the wall, and between his back and the wall, are 0.840 and 0.630, respectively. …
8. ### physics

a climber with a weight of 590 N is held by a belay rope connected to her climbing harness and belay device; the force of the rope on her has a line of action through her center of mass. The indicated angles are θ = 35˚ and …
9. ### physics

consider the 52 kg climber. find the tension in the rope and the force that the climber must exert with her feet on the vertical rock face to remain stationary. assume that the force is exerted parallel to her legs. also, assume negligible …
10. ### Physics

In the figure, a 52 kg rock climber is climbing a “chimney” between two rock slabs. The coefficient of static friction between her shoes and the rock is 1.20; between her back and the rock it is 0.707. She has reduced her push …

More Similar Questions