Question

Two bodies A and B of mass 150 g and 250 g respectively are approaching each other. Both particles have a speed of 3 m/s. Find the magnitude of the total linear momentum of the system of two particles.  

Answer 1

Mass of body A,
= 150 g
= 0.15 kg
Mass of body B,
= 250 g
= 0.25 kg
Both the bodies are moving towards each other. Let the direction of B be taken as positive. Then the direction of A will be considered negative.
Velocity of A,
= - 3 m/s
Velocity of B,
= 3 m/s
Now, total momentum of the system,
P = (0.15)(-3) + (0.25)(3)
=> P = - 0.45 + 0.75
=> P = 0.30 N's

Answer 2

Mass of A,= 150 g = 0.15 kg
Mass of B ,= 250 g = 0.25 kg
Let the velocity of a be negative and b be positive
Velocity of A,  = - 3 m/s
Velocity of B,= 3 m/s
P = (0.15)(-3) + (0.25)(3)
 = 0.30 N