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4-1.Newton's Laws of Motion
normal
A person in an elevator accelerating upwards with an acceleration of $2\,ms^{-2}$ , tosses a coin vertically upwards with a speed of $20\,ms^{-1}$ . After how much time will the coin fall back into his hand ? $(g = 10\,m s^{-2})$
A
$\frac{5}{3}\,s$
B
$\frac{3}{10}\,s$
C
$\frac{10}{3}\,s$
D
$\frac{3}{5}\,s$
Solution
$\therefore \mathrm{t}=\frac{2 \mathrm{v}}{\mathrm{a}+\mathrm{g}}=\frac{2 \times 20 \mathrm{ms}^{-1}}{(2+10) \mathrm{ms}^{-2}}=\frac{40}{12} \mathrm{s}=\frac{10}{3} \mathrm{s}$
Standard 11
Physics
