A river 800m wide flows at the rate of 5km/h . A swimmer who can swim at 10km/h in still water wants to cross the river straight
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1) The final velocity of the two trains is 6 m/s to the right
2) It is an inelastic collision
Explanation:
1)
We can solve this problem by using the law of conservation of momentum: in fact, in absence of external forces, the total momentum of the two trains must be conserved before and after the collision.
Therefore we can write:
where:
is the mass of the first train
is the initial velocity of the first train
is the mass of the second train
is the initial velocity of the second train (initially at rest)
is the final combined velocity of the two trains
Solving the equation for v, we find the final velocity of the two trains:
2)
There are two types of collisions:
- Elastic collision: in an elastic collision, both the total momentum and the total kinetic energy of the system are conserved
- Inelastic collision: in an inelastic collision, only the total momentum is conserved, while the total kinetic energy is not (part of it is converted into thermal energy due to internal frictions)
To verify what type of collision is this, we can compare the total kinetic energy before and after the collision:
Before:
After:
As we can see, the kinetic energy is not conserved, so this is an inelastic collision.
Learn more about momentum here:
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Answer:
Explanation:
Hello!
In this case, for this melting process, we can identify two sub-processes in order to take the stainless steel from solid to liquid:
1. Heat up from 298.15 K to 1673 K.
2. Undergo the phase transition.
Both process have an associated enthalpy as shown below:
Therefore, the required heat is:
Notice the problem is not providing neither the mass or volume, that is why we assumed the mass is 1 g; however, it can be changed to the mass you are given.
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According to Newton's second law, the force applied to an object is equal to the product between the mass of the object and its acceleration:
where F is the magnitude of the force, m is the mass of the object and a its acceleration.
In this problem, the object is the insect, with mass
. The acceleration of the insect is 
, therefore we can calculate the force exerted by the car on the insect:
How do we find the force exerted by the insect on the car?
According to Newton's third law (known as action-reaction law), when an object A exerts a force on an object B, object B also exerts a force equal and opposite on object A. Therefore, the force exerted by the insect on the car is equal to the force exerted by the car on the object, so it is 0.01 N.
where F is the magnitude of the force, m is the mass of the object and a its acceleration.
In this problem, the object is the insect, with mass
How do we find the force exerted by the insect on the car?
According to Newton's third law (known as action-reaction law), when an object A exerts a force on an object B, object B also exerts a force equal and opposite on object A. Therefore, the force exerted by the insect on the car is equal to the force exerted by the car on the object, so it is 0.01 N.