A ball is thrown vertically downwards from a height of 20m with an initial velocity v_o, It collides with the ground, loses 50% of its energy in collision and rebounds to the same height. The initial velocity v_o is,

(Take g = 10 ms^-2)

14 ms^-1

20 ms^-1

28 ms^-1

10 ms^-1

Solution

20 ms^-1

Suppose a ball rebounds with speed v,

$straight v space equals space square root of 2 gh space end root space equals space square root of 2 space straight x space 10 space straight x space 20 space end root space equals space 20 space straight m divided by straight s Energy space of space straight a space ball space just space after space rebound comma straight E space equals space 1 half space mv squared space equals space 200 space straight m As comma space 50 space percent sign space of space energy space loses space in space collision space means space just space before space collision space energy space 400 space straight m. According space to space law space of space conservation space of space energy comma space we space have 1 half space mv subscript 0 superscript 2 space space plus space mgh space equals space 400 space straight m rightwards double arrow space 1 half mv subscript 0 superscript 2 space plus space straight m space straight x space 10 space straight x space 20 space equals space 400 space straight m space rightwards double arrow space straight v subscript straight o space equals space 20 space straight m divided by straight s$

Some More Questions From Work, Energy and Power Chapter

By eating two apples, a person starts pushing the wall of room. If food value of apple is 100 calories per apple, how much work he will do in pushing the wall in one hour?

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Work, Energy And Power

A ball is thrown vertically downwards from a height of 20m with an initial velocity v_o, It collides with the ground, loses 50% of its energy in collision and rebounds to the same height. The initial velocity v_o is,

(Take g = 10 ms^-2)

14 ms^-1

20 ms^-1

28 ms^-1

10 ms^-1

Some More Questions From Work, Energy and Power Chapter

Define the unit joule.

What are different units of energy?

What is watt?

Define watt.

How many joules are there in one eV?

What is the relation between kWh and Joule?

Does the body at rest possess energy?

By eating two apples, a person starts pushing the wall of room. If food value of apple is 100 calories per apple, how much work he will do in pushing the wall in one hour?

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NCERT Sample Papers

Entrance Exams Preparation

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For Daily Free Study Material Join wiredfaculty

Work, Energy And Power

A ball is thrown vertically downwards from a height of 20m with an initial velocity vo, It collides with the ground, loses 50% of its energy in collision and rebounds to the same height. The initial velocity vo is,(Take g = 10 ms-2) 14 ms-1 20 ms-1 28 ms-1 10 ms-1

Some More Questions From Work, Energy and Power Chapter

Define the unit joule.

What are different units of energy?

What is watt?

Define watt.

How many joules are there in one eV?

What is the relation between kWh and Joule?

Does the body at rest possess energy?

By eating two apples, a person starts pushing the wall of room. If food value of apple is 100 calories per apple, how much work he will do in pushing the wall in one hour?

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

A ball is thrown vertically downwards from a height of 20m with an initial velocity v_o, It collides with the ground, loses 50% of its energy in collision and rebounds to the same height. The initial velocity v_o is,

(Take g = 10 ms^-2)

14 ms^-1

20 ms^-1

28 ms^-1

10 ms^-1