- Home
- Standard 11
- Physics
7.Gravitation
medium
$Assertion$ : A tennis ball bounces higher on hills than in plains.
$Reason$ : Acceleration due to gravity on the hill is greater than that on the surface of earth
AIf both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
BIf both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
CIf the Assertion is correct but Reason is incorrect.
DIf both the Assertion and Reason are incorrect.
(AIIMS-2009)
Solution
$\begin{array}{l}
Suppose\,that\,the\,tennis\,ball\,bounces\,\\
with\,a\,velocity\,u.\,It\,will\,go\,up,\,its\,velocity\\
becomes\,zero.\,If\,h\,is\,the\,hgight\,up\,to\,which\\
it\,rises\,on\,the\,hill,\,then\\
\,\,\,\,\,\,\,\,\,\,\,\,{\left( 0 \right)^2} – {u^2} = 2\left( { – g'} \right)h\\
Where\,g'\,is\,acceleration\,due\,to\,gravity\,\\
on\,the\,hill.
\end{array}$
$\begin{array}{l}
\therefore h = \frac{{{u^2}}}{{2g'}}\\
{\rm{since}},\,the\,accleration\,due\,to\,gravity\,on\\
the\,hill\,\left( {g'} \right)\,is\,less\,than\,that\,on\,earth\,\\
\left( {effect\,of\,height} \right),\,it\,follows\,that\,tennis\\
ball\,will\,bounce\,higher\,on\,hills\,than\,in\,\\
plains.
\end{array}$
Suppose\,that\,the\,tennis\,ball\,bounces\,\\
with\,a\,velocity\,u.\,It\,will\,go\,up,\,its\,velocity\\
becomes\,zero.\,If\,h\,is\,the\,hgight\,up\,to\,which\\
it\,rises\,on\,the\,hill,\,then\\
\,\,\,\,\,\,\,\,\,\,\,\,{\left( 0 \right)^2} – {u^2} = 2\left( { – g'} \right)h\\
Where\,g'\,is\,acceleration\,due\,to\,gravity\,\\
on\,the\,hill.
\end{array}$
$\begin{array}{l}
\therefore h = \frac{{{u^2}}}{{2g'}}\\
{\rm{since}},\,the\,accleration\,due\,to\,gravity\,on\\
the\,hill\,\left( {g'} \right)\,is\,less\,than\,that\,on\,earth\,\\
\left( {effect\,of\,height} \right),\,it\,follows\,that\,tennis\\
ball\,will\,bounce\,higher\,on\,hills\,than\,in\,\\
plains.
\end{array}$
Standard 11
Physics
