Explanation:
The total energy gained by the hiker = 140 x 4186 J
This energy is consumed in the potential energy acquired , while climbing up the hill.
The potential energy P.E = mass of hiker x acceleration due to gravity x height
Thus
140 x 4186 = 69 x 10 x h
or h = = 850 m
If the 20% of the total energy is used
the height h₀ = = 170 m
Answer:
31.67 in
Explanation:
Given:
Diameter of the pipe, D = 3ft = 36 in
cross-sectional area of the steel = 0.2 in²
Note: Refer to the figure attached
From the free body diagram represented in the figure, we have
ΣFx = 0
or
pressure × projected area = 2 × Force in steel
Now, the projected area = spacing (s) × diameter of the wood pipe
force in steel = stress in steel (σ) × cross-sectional area of the steel
on substituting the values we get
4 ksi × (s × 36 in) = 2 × σ × 0.2 in²
also, allowable hoop stress = 11.4 ksi
thus,
σ = 11.4 ksi = 11.4 × 10³ psi
therefore, we have
4 psi × (s × 36 in) = 2 × 11.4 × 10³ psi × 0.2 in²
thus,
s = 31.67 in
hence the maximum spacing is 31.67 in
