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Two balls each of mass 1 kg moving in opposite directions with speed 15 m/s collides and rebounds with the same speed. The magnitude of impulse imparted to each ball due to other is

Collisions
NEET
1

15 kg m s⁻¹

2

5 kg m s⁻¹

3

30 kg m s⁻¹

4

10 kg m s⁻¹

Solution:

Let the mass of each ball be m=1m = 1 kg.

Let the initial velocity of one ball be vi=+15\vec{v}_i = +15 m/s.

Since it rebounds with the same speed in the opposite direction, its final velocity is vf=15\vec{v}_f = -15 m/s.

Impulse imparted to this ball is the change in its momentum:

J=Δp=mvfmvi\vec{J} = \Delta \vec{p} = m\vec{v}_f - m\vec{v}_i

J=m(vfvi)=1×(1515)=1×(30)=30\vec{J} = m(\vec{v}_f - \vec{v}_i) = 1 \times (-15 - 15) = 1 \times (-30) = -30 kg m/s.

The magnitude of the impulse is J=30|\vec{J}| = |-30| kg m/s = 30 kg m/s.

Similarly, for the other ball, if its initial velocity was 15-15 m/s, its final velocity would be +15+15 m/s. The impulse would be 1×(15(15))=1×(15+15)=301 \times (15 - (-15)) = 1 \times (15 + 15) = 30 kg m/s. The magnitude is the same.

Thus, the magnitude of impulse imparted to each ball is 30 kg m s⁻¹.