Concepts Of Physics MCQ Edition [Volume 1]PhysicsCentre of Mass, Linear momentum, Collision
If two balls are tossed simultaneously into the air, the acceleration of their centre of mass while in flight
Options
- Adepends on the masses of the two balls
- Bis equal to g
- Cdepends on the direction of motion of the balls
- Ddepends on the speeds of the two balls
Correct answer
B. is equal to g
Step-by-step solution
Let the masses of the two balls be m₁ and m₂ . While in flight, the only force acting on each ball is gravity (ignoring air resistance). The acceleration of the first ball is a ₁ = g and the acceleration of the second ball is a ₂ = g . The acceleration of the centre of mass of the two balls is given by: a _ cm = m₁ a ₁ + m₂ a ₂ m₁ + m₂ Substituting a ₁ = g and a ₂ = g : a _ cm = m₁ g + m₂ g m₁ + m₂ = (m₁ + m₂) g m₁ + m₂ = g Thus, the acceleration of their centre of mass is equal to g downwards, independent of their