Question

Class 10th ICSE question (Physics work energy)..

Answer 1

ANSWER

The kinetic energy of moving body is equal to be the product of the mass(m) of the body and square of its speed(v2).

Kinetic energy =21×mass×(speed)2

i.e., =21mv2

Let mass of man is Mkg and speed is v and speed body is v1, the

21Mv2=21{212Mv12}          ...........(i)

when man speed up by 1m/s, than

v=v+1

∴21M(v+1)2=21{2M}⋅v12     .............(ii)

Dividing Eqs. (i) by (ii), we get

(v+1)2v2=21

2v=v+1

v=2

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