# AP PHYSICS MECH.

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A 5.00 g bullet moving at 648 m/s strikes a 670 g wooden block at rest on a frictionless surface. The bullet emerges, traveling in the same direction with its speed reduced to 440 m/s.
A 5.00 g bullet moving at 648 m/s strikes a 670 g wooden block at rest on a frictionless surface. The bullet emerges, traveling in the same direction with its speed reduced to 440 m/s.
(a) What is the resulting speed of the block?

(b) What is the speed of the bullet-block center of mass?
(b) What is the speed of the bullet-block center of mass?

• AP PHYSICS MECH. -

Momentum before = 648 * .005
equals
Momentum after = 440*.005 + v * .670
solve for v
v = 1.55 m/s

Speed of center of mass does not change because total mass does not change

b)before : average speed = (648*.005 + 0*.670)/.675 = 4.8 m/s

c) after: average speed = (440*.005 + 1.55*.670)/.675 = 4.8 m/s sure enough

• AP PHYSICS MECH. -

Thank you :)

• AP PHYSICS MECH. -

I like birds

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