Two Toy-cars a and Bof Masses 200 G and 500 G Respectively Are Moving with the Same Speed. Which of the Two Has Greater Kinetic Energy ? - Physics

Question

Two toy-cars A and Bof masses 200 g and 500 g respectively are moving with the same speed. Which of the two has greater kinetic energy ?

Solution

CAR A                                            CAR B

mas= 200g                                    mass = 500 g

=200/1000=1/5 kg                     =500/1000=0.5 kg

=0.2kg

K.E.=1/2 MV^2               ∴  speed of both cars
is same

K.E. =1/2× 0.2 ×V^2       K.E. of B=1/2 ×0.5× V^2

=0.1 v^2                                      =0.25 v^2

0.25 v^2 is greater than 0.1v2

∴ K.E. of car B is greater.
Or
Since speed of both cars is same
∴ The speed of car having greater mass (i.e. of car B), the K.E. is greater
∴  Kinetic energy of car B having greater mass is greater.

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Selina Solution for Concise Physics - Middle School for Class 8 ICSE (2020 (Latest))
Chapter 4: Energy
Short/Long Answer questions | Q 24 | Page 78