A block of mass 10 kg, moving in the x-direction with a constant speed of 10 ms^-1 , is subjected to a retarding force F= 0.1x J/m during its travel from x = 20 m to 30 m. Its final KE will be

475 J

450 J

275 J

250 J

Solution

475 J

From work energy theorem
work done = change in KE
⇒ W = K_f -K_i
$rightwards double arrow space straight K subscript straight f end subscript space equals space straight W space plus straight K subscript straight i space end subscript equals space integral subscript straight x subscript 1 end subscript superscript straight x subscript 2 end superscript Fxdx space plus 1 half mv squared equals integral subscript 20 superscript 30 minus 0.1 space straight x space dx space plus 1 half space straight x space 10 space straight x space space 10 squared space equals space minus 0.1 open square brackets straight x squared over 2 close square brackets subscript 20 superscript 30 space plus 500 equals negative 0.50 left square bracket 30 squared minus 20 squared right square bracket space plus 500 equals negative 0.05 left square bracket 900 minus 400 right square bracket plus 500 rightwards double arrow space straight K subscript straight f equals negative 25 plus 500 equals 475 space straight J$

Some More Questions From Work, Energy and Power Chapter

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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Work, Energy And Power

A block of mass 10 kg, moving in the x-direction with a constant speed of 10 ms^-1 , is subjected to a retarding force F= 0.1x J/m during its travel from x = 20 m to 30 m. Its final KE will be

475 J

450 J

275 J

250 J

Some More Questions From Work, Energy and Power Chapter

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?

A man is rowing upstream and is at rest w.r.t. shore. Is he doing work w.r.t. shore?

Is frictional force conservative?

What is the work done by gravitational force in taking the mass m with constant velocity through height h?

A mass is tied with a string and whirled in horizontal circle. What is the work done by tension force?

Does the work done by force depend upon the velocity at that instant?

What is the work done by man against gravity when he is carrying a load on his head and walking on the horizontal road?

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NCERT Sample Papers

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For Daily Free Study Material Join wiredfaculty

Work, Energy And Power

A block of mass 10 kg, moving in the x-direction with a constant speed of 10 ms-1 , is subjected to a retarding force F= 0.1x J/m during its travel from x = 20 m to 30 m. Its final KE will be 475 J 450 J 275 J 250 J

Some More Questions From Work, Energy and Power Chapter

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?

A man is rowing upstream and is at rest w.r.t. shore. Is he doing work w.r.t. shore?

Is frictional force conservative?

What is the work done by gravitational force in taking the mass m with constant velocity through height h?

A mass is tied with a string and whirled in horizontal circle. What is the work done by tension force?

Does the work done by force depend upon the velocity at that instant?

What is the work done by man against gravity when he is carrying a load on his head and walking on the horizontal road?

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

A block of mass 10 kg, moving in the x-direction with a constant speed of 10 ms^-1 , is subjected to a retarding force F= 0.1x J/m during its travel from x = 20 m to 30 m. Its final KE will be

475 J

450 J

275 J

250 J