Question

I need proper explanation for this question not just the option!

else reported !!!! ​

Answer 1

explanation:

T=40 s20=2 s. 

Further, t=nT=20T or Δt=20ΔT

Further, t=nT=20T or Δt=20ΔT 

∴          Δtt=ΔTT∴          Δtt=ΔTT 

or ΔT=Tt.Δt=(240)(1)=0.05 sΔT=Tt.Δt=(240)(1)=0.05 s 

Further, 

T=2π1g−−√ or T∝g−1/2T=2π1g or T∝g−1/2 

∴ΔTT×100=−12×Δgg×100∴ΔTT×100=−12×Δgg×100 

or %% error in determination of g is 

Δgg×100=−200×ΔTTΔgg×100=−200×ΔT/T 

=−200×0.052=−5%=−200×0.052=−5% 

∴∴ Correct options are (a) and (c).

Answer 2

SOLUTION

Error in time period

$= > \frac{least \: count}{20} = \frac{1}{20 } = 0.05s$

Now, total time taken, t= 40s =20× T

$= > T= 2\pi \sqrt{ \frac{l}{g} } \\ \\ = >∴t = nT= 2\pi \: n \sqrt{ \frac{l}{g} } \\ \\ = > {t}^{2} = 4 {\pi}^{2} {n}^{2} \frac{l}{g} \\ \\ = > g = \frac{4 {\pi}^{2} {n}^{2} l }{ {t}^{2} } \\ \\ = > \frac{ \triangle \: g}{g} = \frac{ \triangle \: l}{l} + 2 \frac{ \triangle \:t}{t} = 0 + 2 \times \frac{1}{40} = \frac{1}{20} \\ \\ = >∴ \frac{ \triangle \: g}{g} \times 100 \\ \\ = > So, (\frac{1}{20} \times 100 )\% = 5\%$

The correct options are A & C.

Hope it helps ☺️