Question

Hey !!

⚫ Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions. The velocity of eachobject is 2.5 m s-1 before the collision during which they stick together. What will be the velocity of the combined object after collision?

⚫ Class :- 9th

⚫ Subject :- Physics

Answer 1

Hi there !!
Here's your answer

Given that

Mass of the 1st object (m1) = 1.5 kg
Velocity of the 1st object before collision (u1) = 2.5m/s
p = m1u1 = 1.5kg × 2.5m/s = 3.75kgm/s

Mass of the 2nd object (m2) = 1.5kg
Velocity before collision (u2) = -2.5m/s [ negative sign indicates direction opposite to that of motion ]
p = m2u2 = 1.5kg × -2.5m/s = -3.75kgm/s

Let the final velocity of the object be v , since the Velocities will be equal at collision,
we have,

m1u1 + m2u2 = m1v + m2v

m1u1 + m2u2 = v(m1 + m2)

3.75 - 3.75 = v(1.5 + 1.5)

0 = 3v

v = 0

Thus,
the velocity of the combined object after collision will be 0m/s.

Answer 2

Hey there ‼
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Mass of one of the objects, m1 = 1.5 kg

Mass of the other object, m2 = 1.5 kg 

Velocity of m1 before collision, u1 = 2.5 m/s

Velocity of m2, moving in opposite direction before collision, u2 = −2.5 m/s

Let v be the velocity of the combined object after collision.

By the law of conservation of momentum,
Total momentum after collision = Total momentum before collision, 

Or (m1 + m2) v = m1u1 + m2u2
=> ( 1.5 + 1.5 ) v = ( 1.5 × 2.5 ) + ( 1.5 × –2.5 )
=> 3v = 3.75 – 3.75
=> 3v = 0
=> v = 0 / 3
=> v = 0

Therefore, the velocity of the combined object after collision is 0 m/s.
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Hope my ans.'s satisfactory. (^-^)