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Flying Bird ~ Q & A

 Q: A bird while flying takes a right turn, where does it get the centripetal force from? A: The centripetal force is provided by the bird’s wings as it changes the direction of its flight. As the bird turns to the right, it must adjust the angle of its wings to produce a component of the force towards the center of the turn.
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Why Rains Block Vision?

 Which phenomenon of light is responsible for rain blocking the vision? (A) Total internal reflection (B) Dispersion (C) Interference (D) Scattering
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Motion on Long Railroad Car

A boy standing at the rear end of a long railroad car throws a ball vertically upwards. The car is moving on the straight horizontal road with a deceleration of $1 m/s^2$ and the projection velocity in the vertical direction is 10 m/s. How far ahead of the boy will the ball fall on the car? Assume that the car keeps on moving throughout the motion of the ball. [$g=10 m/s^2$]
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Car ~ Turning OR Braking

A car driver going at some speed v engaged in phone call all of a sudden finds a wide wall at a distance d. Are hard brakes applied in panic or car suddenly turned in a circle of radius d more likely to avoid collision with the wall? Assume that the driving balance is not lost.
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$1.005^{200}$ Vs 2

 Select the correct option: (A) $1.005^{200} < 2$ (B) $1.005^{200} = 2$ (C) $1.005^{200} \leq 2$ (D) $1.005^{200} > 2$
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The ranges and heights for two projectiles projected ....

The ranges and heights for two projectiles projected with the same initial velocity at angles $42^\circ $ and $48^\circ $ with the horizontal are $R_1\,,R_2$ and $H_1\,,H_2$ respectively. Choose the correct option: (A) $R_1 < R_2 $ and $H_1 < H_2 $ (B) $R_1 > R_2 $ and $H_1 = H_2 $ (C) $R_1 = R_2 $ and $H_1 = H_2 $ (D) $R_1 = R_2 $ and $H_1 < H_2 $ Solution $R=\frac {u^2 sin 2\theta }{g} $, $H=\frac {u^2 sin^2 \theta }{2g}$  $\frac {R_1}{R_2} = \frac {sin 2 \times 42^\circ}{sin 2\times 48^\circ} = \frac {cos 6^\circ}{cos 6^\circ} = 1 $ $\frac {H_1}{H_2}= \frac {sin^2 42^\circ }{sin^2 48^\circ } = tan^2 42^\circ < 1 $ Answer: (D)
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