A 98-kg fullback is running along at 8.6 m / s when a 76-kg defensive back running in the same direction at 9.8 m / s jumps on h
1 answer:
The total momentum before and after the collision must be conserved.
The total momentum before the collision is:
where m1 and m2 are the masses of the two players, and
and 
their initial velocities. Both are considered with positive sign, because the two players are running toward the same direction.
The final momentum is instead
because now the two players are moving together with a total mass of (m1+m2) and final speed vf.
By requiring that the momentum is conserved
we can calculate vf, the post-collision speed:
and the direction is the same as the direction of the players before the collision.
The total momentum before the collision is:
where m1 and m2 are the masses of the two players, and
The final momentum is instead
because now the two players are moving together with a total mass of (m1+m2) and final speed vf.
By requiring that the momentum is conserved
we can calculate vf, the post-collision speed:
and the direction is the same as the direction of the players before the collision.
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To calculate the change in kinetic energy, you must know the force as a function of position. The work done by the force causes the kinetic energy change
Explanation:
The work-energy theorem states that the change in kinetic enegy of an object is equal to the work done on the object:
where the work done is the integral of the force over the position of the object:
As we see from the formula, the magnitude of the force F(x) can be dependent from the position of the object, therefore in order to solve correctly the integral and find the work done on the object, it is required to know the behaviour of the force as a function of the position, x.