A bullet of mass m is moving horizontally with speed V_o when it hits a block of
ID: 1587939 • Letter: A
Question
A bullet of mass m is moving horizontally with speed V_o when it hits a block of mass 100m that is at rest on a horizontal frictionless table, as shown above. The surface of the table is a height h above the floor. After the impact, the bullet and the block slide off the table and hit the floor a distance x from the edge of the table. Derive expressions for the following quantities in terms of m, h, V_o, and appropriate constants: the speed of the block as it leaves the table the change in kinetic energy of the bullet-block system during impact the distance x Suppose that the bullet passes through the block instead of remaining in it. State whether the time required for the block to reach the floor from the edge of the table would now be greater, less, or the same. Justify your answer. State whether the distance x for the block would now be greater, less, or the same. Justify your answer.Explanation / Answer
a) speed of the block = v0 / 101 ( initial mometum/total mass combined )
b) change in KE = 0.5(mv0^2 -m*v0^2/101) = 0.5mv0^2 *(100/101)
c) time taken to land on floor after leaving the table = sqrt (2h/g)
hence x = v0 / 101 *sqrt (2h/g)
d) time taken to land on floor after leaving the table = sqrt (2h/g) , and it is independent of the blocks horizontal speed . so the time will remain same .
e) now that the bullet has crossed the block the block will attain a lesser horizontal velocity . hence x will be smaller in this case.
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