# Answer on Mechanics | Relativity Question for Chalani Jayawardena

Question #3618

A = 8kg , 10 ms-1 and moves to East

<br>B = 5kg , 20ms-1 and moves to North

<br>-Before Hitting-

<br>

A+B = 13kg<br>& -After Hitting-

<br>

if the hitting is fully unelastic, find the velocity of A and B after hitting.What is the direction that A+B moves after hitting.

<br>B = 5kg , 20ms-1 and moves to North

<br>-Before Hitting-

<br>

A+B = 13kg<br>& -After Hitting-

<br>

if the hitting is fully unelastic, find the velocity of A and B after hitting.What is the direction that A+B moves after hitting.

Expert's answer

We should add the& vectors& of impulse A and B

Pa = MaVa = 8*10 = 80 kg*m/s (to the East)

Pb = MbVb& = 5*20 = 100 kg m/s (to the North)

The modulus of the impulse after inelastic hitting is

radic; (Pa2 + Pb2) = raidc; (802 + 1002) = 128.1 kg m/s

The speed :

128.1 / (8 + 5) = 9.85 m/s

tan (angle to the North) = 80/100 = 0.8

38.66 degrees from North to East.

Pa = MaVa = 8*10 = 80 kg*m/s (to the East)

Pb = MbVb& = 5*20 = 100 kg m/s (to the North)

The modulus of the impulse after inelastic hitting is

radic; (Pa2 + Pb2) = raidc; (802 + 1002) = 128.1 kg m/s

The speed :

128.1 / (8 + 5) = 9.85 m/s

tan (angle to the North) = 80/100 = 0.8

38.66 degrees from North to East.

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## Comments

Assignment Expert15.07.2011 10:55You are welcome!

Chalani Jayawardena15.07.2011 07:30Thank you so much for helping me...And I'm really sorry for my bad English..

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