Question

A body standing on a long railroad car throws a ball straight upwards, the car is moving on the horizontal road with an acceleration $1m{s}^{-2}$. The vertical velocity given is $9.8m{s}^{-1}$. How far behind the boy the ball will fall on the railroad car?

• A. $1m$
• B. $\frac{3}{2}m$
• C. $\frac{7}{4}m$
• D. $2m$

Answer 1

The correct option is D $2m$

For vertical direction we see that the relative distance travelled is zero. Thus
$s_{rel}=ut+\frac{1}{2}a{t}^2\Rightarrow 0=9.8t-\frac{1}{2}{9.8t}^2\Rightarrow t=2s.$

Now for horizontal direction we have
$s=ut+\frac{1}{2}a{t}^{2}s=0+\frac{4}{2}=2m$