A force of 7 pounds stretches a spring 7 inches. Find the work done in stretching this spring 10 inches beyond its natural length.
A) foot-pounds
B) foot-pounds
C) foot-pounds
D) foot-pounds

Question

A force of 7 pounds stretches a spring 7 inches. Find the work done in stretching this spring 10 inches beyond its natural length.
A) foot-pounds 
B) foot-pounds 
C) foot-pounds 
D) foot-pounds

Quizplus · Accepted Answer

First, we can use Hooke's Law to find the spring constant of this spring: 
k = F/x = 7 pounds / 7 inches = 1 pound/inch

Then, we can use the formula for the work done by a spring: 
W = (1/2)kx^2

To find the work done in stretching the spring 10 inches beyond its natural length, we plug in x = 10: 
W = (1/2)(1 pound/inch)(10 inches)^2 = 50 foot-pounds

Therefore, the answer is C, 11eaa88b_9198_9d65_a696_73d2a7d12341_TB5869_11 foot-pounds (rounded to two decimal places).

A Force of 7 Pounds Stretches a Spring 7 Inches