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.

Answer 1

Answer:

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

Step-by-step 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.