Two identical objects are moving directly to-
ward one another at the same speed v.
~v −~v
m m
What is the total kinetic energy of the sys-
tem of the two objects?
1. None of these
2. mv2 since energy is a scalar
3. Zero since (~v −~v)2 = 0
4. Still
1
2
mv2 from the definition of kinetic
energy
5. 4mv2 since (2 v)2 = 4 v2

Question

Two identical objects are moving directly to-
ward one another at the same speed v.
~v −~v
m m
What is the total kinetic energy of the sys-
tem of the two objects?
1. None of these
2. mv2 since energy is a scalar
3. Zero since (~v −~v)2 = 0
4. Still
1
2
mv2 from the definition of kinetic
energy
5. 4mv2 since (2 v)2 = 4 v2

xishem · Answer

Energy is not a vector, and so does not act as a vector addition. You'd calculate each KE separately and sum them up as scalars.

anonymous · Answer

yeah i chose option 4 and its wrong

anonymous · Answer

it says 1/2mv^2 but it be the KE of the first plus the KE of the second

kunal · Answer

i think in the earth frame of reference it will be mv^2...i.e. sum of of individual K.E.s

anonymous · Answer

so option 2

kunal · Answer

yes....

anonymous · Answer

ill try it