Answer:
When a particle or a system of particles move in a system where no external force acts, then the total linear momentum of the particle system remains constant.
Explanation:
Given data:
Total mass of the skateboarder, 
Mass of the friend, 
Initial velocity of the skateboarder, 
Initial velocity of the the friend, 
Let the new velocity of the skateboarder when his friend jumps be 
.
From the conservation law of linear momentum,
<span>First draw a free-body diagram. Torque T = Force F x Distance d where force is the component of gravitational force g and d is the lever arm distance to the pivot point. Since the pivot point is at the back tire we subtract that from the length of the car resulting in d = 1.12 - 0.40 = 0.72 meters = d. We are interested in the perpendicular component of the force exerted on the car jack so use sin 8 degrees then T=1130 kg x 9.81 m/s^2 x sin(8 degrees) x0.72 m = 1,110.80 Newton-meters</span>
If the acceleration of a moving object is zero, the object remains at a constant speed (without friction)
When an atom becomes electrically charged the number of electrons or protons stops and they are not equal again. The "extra" electron or proton is not balanced by something inside the atom any longer and it starts attracting itself to othet protons or electrons in other atoms.
<h3>What is atomic structure?</h3>
An atomic structure comprises of positively charged nucleus which is surrounded by negatively charged particles called electron and neutron which is neutral charged.
Unlike charges attract each other while like charges repel each other.
Therefore, When an electron is fully charged, the number of electrons will stop to be unequal again.
Learn more about Atomic charge here.
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