The sun, fire and lamp because they generate their own light.
The momentum does not stop till both objects are at a complete stop
The correct answer for the question that is being presented above is this one: "D.
Property Electric Field Magnetic Field
<span>Can be produced by moving electric charge X </span>
Have two sides with opposite characteristics X X
Can make metals, such as nickel, iron, and cobalt, into magnets X X
<span>Can be turned on or off with a switch X"</span>
Conservation of momentum: total momentum before = total momentum after
Momentum = mass x velocity
So before the collision:
4kg x 8m/s = 32
1kg x 0m/s = 0
32+0=32
Therefore after the collision
4kg x 4.8m/s = 19.2
1kg x βm/s = β
19.2 + β = 32
Therefore β = 12.8 m/s