Physics Two Dimensional Motion Question 221
Question: A ball is rolled off the edge of a horizontal table at a speed of 4 m/second.It hits the ground after 0.4 second.Which statement given below is true
Options:
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 4.0 m/second C) Height of the table is 0.8 m D) It hits the ground at an angle of $ 60^{o} $ to the horizontal
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Answer:
Correct Answer: A , C
Solution:
(a,c) Vertical component of velocity of ball at point P $ v _{V}=0+gt=10\times 0.4=4,m/s $ Horizontal component of velocity = initial velocity $ \Rightarrow v _{H}=4,m/s $ So the speed with which it hits the ground $ v=\sqrt{v _{H}^{2}+v _{V}^{2}}=4\sqrt{2},m/s $ and $ \tan \theta =\frac{v _{V}}{v _{H}}=\frac{4}{4}=1 $
Therefore $ \theta =45{}^\circ $ It means the ball hits the ground at an angle of $ 45{}^\circ $ to the horizontal. Height of the table $ h=\frac{1}{2}gt^{2}=\frac{1}{2}\times 10\times {{(0.4)}^{2}}=0.8,m $ Horizontal distance travelled by the ball from the edge of table $ h=ut=4\times 0.4=1.6,m $
Same us above
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