A ball starts falling down from rest from an initial height of h = 20 m . With a gun held horizontally, d = 50 m far from the trajectory of the falling ball, at the height of h ′ = 10 m , we are going

Question

A ball starts falling down from rest from an initial height of $h = 20 m$ . With a gun held horizontally, $d = 50 m$ far from the trajectory of the falling ball, at the height of $h^{'} = 10 m$ , we are going to shoot at the falling ball. The bullet leaves the gun at a speed of $v = 100 m / s$ . At what time after the start of the fall should the gun be fired in order to hit the falling ball with the bullet? (The air resistance is negligible.)

Question diagram: A ball starts falling down from rest from an initial height

Answer:

1.00

Solution:

$t_{2} = \frac{50}{100} = \frac{1}{2}$

$10 + \frac{5}{4} = 5 t_{1}^{2}$

$t_{1} = \frac{3}{2}$

$t_{1} - t_{2} = \frac{3}{2} - \frac{1}{2} = 1$

TestHub · Accepted Answer

t 2 ​ = 100 50 ​ = 2 1 ​ 10 + 4 5 ​ = 5 t 1 2 ​ t 1 ​ = 2 3 ​ t 1 ​ − t 2 ​ = 2 3 ​ − 2 1 ​ = 1

Physics - Kinematics Question with Solution | TestHub

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