Ratio of the weights of a 1kg block of iron and 1kg block of wood as measured by a spring balance is:
Given: Density of iron =7800kg/m3, density of wood =800kg/m3 and density of air =1.293kg/m3
A
1.5
No worries! Weāve got your back. Try BYJUāS free classes today!
B
2.0015
No worries! Weāve got your back. Try BYJUāS free classes today!
C
1.0015
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
3.0015
No worries! Weāve got your back. Try BYJUāS free classes today!
Open in App
Solution
The correct option is C1.0015 FBD of the block:
Applying equilibrium condition i.e ∑F=0 along vertical direction. Considering air as a fluid, it will exert buoyant force on block. ⇒T+Fb−mg=0 ⇒T=mg−Fb ⇒T=mg−ρagV...(1) [ρa→density of air]
From Eq.(i) for iron block: T1=mg−ρagVi
where Vi→volume of iron block ⇒T1=(1×10)−1.293×10×17800 [∵Vi=mρi] ⇒T1=9.9983N
Similarly, for wooden block , T2=mg−ρagVw [Vw=mρw] ⇒T2=(1×10)−1.293×10×1800 ⇒T2=9.9838N
On dividing T1&T2, T1T2=9.99839.9838 ∴T1:T2=1.0015
Ratio of weights of iron and wooden block of mass 1kg is 1.0015.