Question

The friction of the air causes vertical retardation equal to one tenth of the acceleration due to gravity (Take g = 10 ms^–2). The time of flight will be decreased by

• A. 0%
• B. 1%
• C. 9%
• D. 11%

Answer 1

Answer: (C)

9%

Answer 2

$T = \frac{2u\sin\theta}{g}$ $\therefore\frac{T_{1}}{T_{2}} = \frac{g_{2}}{g_{1}} = \frac{g + \frac{g}{10}}{g} = \frac{11}{10}$

Fractional decrease in time of flight $= \frac{T_{1} - T_{2}}{T_{1}} = \frac{1}{11}$

Percentage decrease = 9%