Question

A stone that is thrown upwards is caught by the thrower himself after 10 seconds. What is the total distance travelled by the ball? (Neglect air friction and take $g=10m/s^2$)

• A. $125m$
• B. $250m$
• C. $0m$
• D. $200m$

Answer 1

The correct option is B $250m$

The ball goes up and comes down, we know that the time taken for the ball to reach the highest point is $\frac{10}{2}=5$ seconds. For the first 5 seconds, the ball goes up and for the next 5 seconds, the ball comes down.
For the first half, $v=0$ (velocity at highest point is 0), $a=-g,t=5s$
$v=u+at$ $\Rightarrow 0=u-10\times 5\Rightarrow u=50m/s$
$s=ut+\frac{1}{2}a{t}^2=50\times 5-5^3=125m$
The ball covers $125m$ while going up, so while coming down it should cover $125m$.

The total distance: $=125+125=250m$