Question

A ball rolls off a horizontal shelf a height h above the floor and takes 0.5s to hit. For the ball to take 1.0s to reach the floor the shelf's height above the floor would have to be___. A) 2h B)3h C) sqrt(2) h D)4h

Answer 1

Answer:

For the ball to take 1.0 s to reach the floor the shelf's height above the floor would have to be 4 h.

Explanation:

According to second equation of motion, the height or the distance covered by an object is given by :

$s=ut+\dfrac{1}{2}at^2$

Since, the ball rolls so the initial vertical component of velocity will be equal to 0. From above equation it is clear that,

$h\propto t^2$

Let h be the height above the floor when the ball taken 0.5 s to hit. At 1 s the ball is H height above the floor.

So, $\dfrac{h}{H}=\dfrac{kt_1^2}{kt_2^2}$

$\dfrac{h}{H}=\dfrac{0.5^2}{1^2}$

After solving, H = 4 h

Hence, for the ball to take 1.0 s to reach the floor the shelf's height above the floor would have to be 4 h.

Answer 2

Distance in a minute=0.5 times 30=15 meters
distance in a second=15 divided by 60=0.25 meters per second
hope it helps