Liz has designed a sailboat. She wants to build a prototype of the boat. Liz has $12,000 to spend on the boat. $7,000 of that mo
ney is budgeted for wood. Liz needs 500 ft of wood planks.
Assuming that Liz will use only one type of wood for her entire project, which of the following could she use to stay on budget?
A. Marine plywood only.
B. She could use any of these woods listed.
C. Marine plywood of Douglas for only.
D. Marine plywood, Douglas fir, or white oak only
Assuming that Liz will use only one type of wood for her entire project, which of the following could she use to stay on budget?
A. Marine plywood only.
B. She could use any of these woods listed.
C. Marine plywood of Douglas for only.
D. Marine plywood, Douglas fir, or white oak only
2 answers:
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Answer:
The percentage change in resistance of the wire is 69%.
Explanation:
Resistance of a wire can be determined by,
R = (ρl) ÷ A
Where R is its resistance, l is the length of the wire, A its cross sectional area and ρ its resistivity.
When the wire is stretched, its length and area changes but its volume and resistivity remains constant.
= 1.3l, and
=
So that;
= (ρ
) ÷
= (ρ × 1.3l) ÷ (
)
= (1.3lρ) ÷ ()
= × [(ρl) ÷ A]
= 1.69R (∵ R = (ρl) ÷ A)
= 1.69R
Where is the new resistance,
is the new length, and
is the new area after stretching the wire.
The change in resistance of the wire = - R
= 1.69R - 1R
= 0.69R
The percentage change in resistance = × 100
= 0.69 × 100
= 69%
The percentage change in resistance of the wire is 69%.