A ball is rolled off the edge of a horizontally table at as speed of `4 m//s`. It hits the ground after `0.8 s`.
(i) it hits the ground at a horizontal distance `3.2 m` from the edge of the table
(ii) The speed with which it hits the ground is `4sqrt(5) m//s`
(iii) Height of the table is `3.2 m`
(iv) it hits the ground at an angle of `tan^(-1)(2)` to the horizontally

Options

A. (i), (ii)
B. (ii), (iii), (iv)
C. (i), (ii), (iii)
D. all option are correct

Answer

D

Explanation

`t = 0.8 s`
(i) `x = u t = 4 xx 0.8 = 3.2 m`
(ii) `v_(x) = u = 4, v_(y) = g t = 10 xx 0.8 = 8`
`v = sqrt(v_(x)^(2) + v_(y)^(2)) = sqrt((4)^(2) + (8)^(2)) = 4sqrt(5) m//s`
(iii) `y = h = (1)/(2) g t^(2) = (1)/(2) xx 10(0.8)^(2) = 3.2 m`
(iv) `tan alpha = (v_(y))/(v_(x)) = (8)/(4) rArr alpha = tan^(-1)(2)`