A 8700-kgkg boxcar traveling at 14 m/sm/s strikes a second boxcar at rest. The two stick together and move off with a speed of 5.0 m/sm/s. What is the mass of thesecond car?

m₂ = 15660 kg

Explanation:

Given that,

Before collision,

Mass of box car 1, m₁ = 8700 kg

Speed of box car 1, u₁ = 14 m/s

Speed of box car 2, u₂ = 0 (at rest)

After collision,

The two stick together and move off with a speed of 5 m/s

Let m₂ is the mass of the second car. As cars stick together, it is a case of inelastic collision. Using the conservation of momentum as follows :

So, the mass of the second car is 15660 kg.

measuring things 1 litre of water

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.