An 8.0 g bullet is fired from a gun at 120 m/s into a 2.0 kg block of wood sitting on a fence post. if the bullet hits the wood and remains in it, what is the speed of the block after the collision?

Explanation:

As we know that bullet strike the block and fix in it

so here if bullet and box is taken as a system then there is no external force on it

so here the initial momentum of bullet and block must be equal to final momentum of bullet and block

so here we have

now we have

now from above equation we have

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

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hope this !