Question

a boy of mass of 70 kg running at 3 metre per second jumps on a stationary trolley of mass 20 kg if both start moving together then find the common velocity​

Answer 1

Answer:

$\huge{Common\:velocity\:=\:2.33m/s}$

Explanation:

Given:

• Mass of the boy(m1) = 70kg
• Mass of the trolley(m2) = 20kg
• Velocity of the boy(u1) = 3m/s
• Velocity of the trolley(u2) = 0m/s

To Find:

• Common velocity of the system(V)

Solution:

→ By conservation of momentum, momentum before the collission is equal to momentum after collission, which is given by

• (m1v1) + (m2u2) = (m1+m2) V

→ Substitute the given datas in the equation, we get

           ( 70×3 ) + ( 20×0 ) = ( 70+20 )V

       ⇒ V = 210/90

       ⇒ V = 2.33m/s

Notes:

• Momentum is the product of mass and velocity. It's unit is kgm/s.
• Momentum is conserved in an isolated system.
• The law of conservation of momentum state that the momentum before collission is equal to the momentum after collission.