This question is written wrong, I think u meant 20 kg?
I hope you are referring to Newton's Laws of Motion by "Newton's Law".
There are three laws quoted by the great physicist of all time Sir Isaac Newton.
These laws are the building-blocks of the field of the Physics known as Classical Physics or Classical Mechanics.
Law 1. If no force applied externally, then a body in rest will always be in rest and a body in motion will continue to move in a straight line with a uniform velocity.
Law 2. The rate of change of momentum is directly proportional to the force applied and the direction of motion is always in the direction of the force applied.
Law 3. Every action has an equal and opposite reaction.
The Law 1 is also called the law of Inertia.
From the 2nd law, we can derive the equation of force, that is F =m.a (m = mass; a = acceleration)
C.energy
The law of conservation of energy says that energy can neither be created nor destroyed.
Mass of first car = Initial mass (Mi) = 2 kg
Initial velocity (Vi) = 2 m/s
Mass of both cars together = Final mass (Mf) = 2 + 3 kg = 5 kg
Final Velocity (Vf) = ?
Applying law of conservation of momentum,
Mi x Vi = Mf x Vf
2 x 2 = 5 x Vf
Vf = 4/5 = 0.8 m/s
vf = 10 m/s. A ball with mass of 4kg and a impulse given of 28N.s with a intial velocity of 3m/s would have a final velocity of 10 m/s.
The key to solve this problem is using the equation I = F.Δt = m.Δv, Δv = vf - vi.
The impulse given to the ball with mass 4Kg is 28 N.s. If the ball were already moving at 3 m/s, to calculate its final velocity:
I = m(vf - vi) -------> I = m.vf - m.vi ------> vf = (I + m.vi)/m ------> vf = I/m + vi
Where I 28 N.s, m = 4 Kg, and vi = 3 m/s
vf = (28N.s/4kg) + 3m/s = 7m/s + 3m/s
vf = 10 m/s.
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