A) it hits the ground at a horizontal distance 1.6 m from the edge of the table
B) the speed with which it hits the ground is 0.4m/second
C) height of the table is 0.8 m
D) it hits the ground at an angle of\[45{}^\circ \]to the horizontal
Correct Answer: B
Solution :
: Initial velocity of 4 m/s is in horizontal direction [a] Horizontal distance\[=4\times 0.4=1.6\text{ }m\]. This is true. [b] Vertical speed gained\[v=g\times t\] \[=10\times 0.4=4\text{ }m/s\] \[\therefore \] \[{{(velocity)}^{2}}={{(4)}^{2}}+{{(4)}^{2}}\] \[\therefore \]velocity \[=4\sqrt{2}\] This is not true. [c] Height of table \[=H\] \[H=\frac{1}{2}g{{t}^{2}}=\frac{1}{2}\times 10\times {{(0.4)}^{2}}=0.8\,m\] or \[H=0.8\text{ }m\] This is true. [d] Angle at the ground \[=\theta \] \[\tan \theta =\frac{vertical\text{ }speed}{horizontal\text{ }speed}=\frac{4}{4}=1\] \[\therefore \] \[\theta =45{}^\circ \] This is true. [b] is not true.
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