Question

In a lab experiment, a student is trying to apply the conservation of momentum. Two identical balls, each with a mass of 1.0 kg.

roll toward each other and collide. The velocity is measured before and after each collision. The collected data is shown below. Which trial shows the conservation of momentum in a closed system?​

Answer 1

Answer: (B) Trial 2

Step-by-step explanation: I just took the test :)

Answer 2

Trial- 2 shows the conservation of momentum in a closed system.

Explanation:

Given: Mass of balls are
`m= 1.0\ kg`

Conservation of momentum in a closed system occurs when momentum before collision is equal to momentum after collision.

• Let initial velocity of ball
  `A\ is\ u_1`
• Initial velocity of ball
  `B\ is\ u_2`
• Final velocity of ball
  `A\ is\ v_1`
• Final velocity of ball
  `B\ is\ v_2`
• Momentum before collision
  `= mu_1+mu_2`
• Momentum after collision
  `=mv_1+mv_2`

Now, According to conservation of momentum.

Momentum before collision = Momentum after collision

`mu_1+mu_2=mv_1+mv_2`

We will plug each trial to this equation.

Trial 1

`mu_1+mu_2=mv_1+mv_2\\1.0(1)+1.0(-2)=1.0(-2)+1.0(-1)\\1-2=-2-1\\-1=-3`

Trial 2

`mu_1+mu_2=mv_1+mv_2\\1.0(.5)+1.0(-1.5)=1.0(-.5)+1.0(-\.5)\\.5-1.5=-.5-.5\\-1=-1`

Trial 3

`mu_1+mu_2=mv_1+mv_2\\1.0(2)+1.0(1)=1.0(1)+1.0(-2)\\2+1=1-2\\3=-1`

Trial 4

`mu_1+mu_2=mv_1+mv_2\\1.0(.5)+1.0(-1)=1.0(1.5)+1.0(-1.5)\\.5-1=1.5-1.5\\-.5=0`

We can see only Trial 2 satisfies the princple of conservation of momentum. That is momentum before collison should equal to momentum after collision.