On a very muddy football field, a 110-kg linebacker tackles an 85-kg halfback. Immediately before the collision, the linebacker is slipping with a velocity of 8.8 m/s north and the half-back is sliding with a velocity of 7.2 m/s east. What is the velocity (magnitude and direction) at which the two players move together immediately after the collision?

Explanation:

mass of line backer, m1 = 110 kg

mass of half back, m2 = 85 kg

initial velocity of line backer, u1 = 8.8 m/s north = 8.8 j

initial velocity of the half back, u2 = 7.2 m/s east = 7.2 i

Use conservation of momentum

m1 x u1 + m2 x u2 = (m1 + m2) x v

where, v is the velocity of the combined mass

110 x 8.8 j + 85 x 7.2 i = (110 + 85) x v

968 j + 612 i = 195 v

v = 4.96 j + 3.14 i

The magnitude of velocity is

v = 5.87 m/s

θ = 57.7°

hypothesising or postulating

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me