Spring P and Q are similar. What is the length of spring P in figure(iv)?

Asked by a.behera67 | 7th Jan, 2016, 07:25: PM

Expert Answer:

Given that the length of the spring is 3 cm
In case (ii), the length of the spring is 6 cm when a weight of 2 N is attached.
e = 6 cm - 3 cm = 3 cm = 0.03 m and F = 2 N
Using, F = e × k ....... (Where, k is the spring constant)
→ 2 N = 0.03 × k 
→ k = 66.66 N/m
 
17.
Force needed to stretch spring P,  FP = e × kP
Force needed to stretch spring Q,  F= e × kQ
Thus, the weight supported by both the springs, W = FFQ  = ekP + ekQ = ekeff
where keff = k+ kQ =  66.66 +  66.66 = 133.32 N/m
Here, W = 8 N
Substituting the values, we get
8 N = e × 133.32 N/m
→e = 0.060 m
Length of the spring = 0.03 m + e = 0.03 m + 0.06 m = 0.09 m 
Or length of spring P = 9 cm

Answered by Yashvanti Jain | 8th Jan, 2016, 12:15: PM