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A stone is dropped from rest from the top of a $20\text{ m}$ tower. Its speed on hitting the ground is ($g = 10\text{ m/s}^2$):
Using $v^2 = u^2 + 2gh = 0 + 2(10)(20) = 400$
$v = \sqrt{400} = \mathbf{20\text{ m/s}}$
Given that $ds \neq 0$:
Compare:
Column A: The time required to travel $d$ miles at $s$ miles per hour
Column B: The time required to travel $\frac{d}{4}$ miles at $2s$ miles per hour
Calculate each time using the formula $\text{time} = \frac{\text{distance}}{\text{speed}}$:
- Column A: $t_A = \frac{d}{s}$
- Column B: $t_B = \frac{d/4}{2s} = \frac{d}{8s}$
To compare, find the ratio: $\frac{t_A}{t_B} = \frac{d/s}{d/(8s)} = \frac{d}{s} \times \frac{8s}{d} = 8$
So $t_A = 8 \times t_B$, meaning Column A is 8 times larger than Column B.
Therefore, Column A is greater.
The Oral Polio Vaccine (OPV) is the most heat-sensitive of all vaccines used in the Expanded Programme on Immunization (EPI). It must be stored at -15Β°C to -25Β°C at the national and provincial level. However, at the district/peripheral level, OPV can be stored at +2Β°C to +8Β°C for short periods. The option -15Β°C to -25Β°C is the standard cold chain requirement. Mismanagement of cold chain is a leading cause of vaccine failure β a Head Nurse must strictly monitor this.
Which alkali metal forms only normal oxide (MβO) with oxygen?
Lithium forms only LiβO (normal oxide). Na forms NaβOβ (peroxide); K, Rb, Cs form superoxides (MOβ).
Time period: $T = \frac{5}{10} = 0.5\ \text{s}$
Formula for oscillation: $T = 2\pi\sqrt{\frac{I}{MB}}$
$B = \frac{4\pi^2 I}{MT^2} = \frac{4 \times 9.85 \times 5\times10^{-6}}{9.85\times10^{-2} \times (0.5)^2}$
$= \frac{4 \times 9.85 \times 5\times10^{-6}}{9.85\times10^{-2} \times 0.25} = \frac{20\times10^{-5}}{2.4625\times10^{-3}} = 0.01\ \text{T} = 10\ \text{mT}$
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