When 2.5kg weight of hero's hand hits the villain of 80kg,in a movie,the villain moves with 12.5ms-1 and hits a transformer near by.what will be the speed of hero's hand compared to bullet fired from a gun(here speed of bullet is 370ms-1)?

Is the speed of hand is greater or lesser than bullet speed?

1 Answer
yumean1119
Dec 27, 2017

The speed of hero's hand is about #1.08# times greater than the bullet speed.

Explanation:

To solve this, use the law of momentum conservation.

Suppose two obejects A(#=m_1#) and B(#=m_2#) have a collision at a speed of #v_1# and #v_2#, and the speed after the collision are #v_1'# and #v_2'#, respectively.

The formula is
#m_1v_1+m_2v_2=m_1v_1' + m_2v_2'#.

Put the following values to the formula.
#m_1=2.5# kg (mass of the hero's hand)
#m_2=80# kg (mass of the villain)
#v_2'=12.5# m/s (speed of the villain after collision)
#v_2=0#, #v_1'=0# (assumption)

Then,
#2.5v_1=80*12.5#
#v_1=400# m/s
is the speed of the hero's hand before hitting the villain.

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