- #1
Kmol6
- 15
- 1
Homework Statement
A bullet is fired vertically into a 1.40 kg block of wood at rest directly above it. If the bullet has a mass of 29.0 g and a speed of 510 m/s, how high will the block rise after the bullet becomes embedded in it?
Homework Equations
1. m1v1 +m2v2 = mfvf
2. x=xo +vot +1/2at2
3. Quadratic formula
The Attempt at a Solution
1.
(.029kg)(510m/s) + 0 = (1.42)(vf)
10.4 m/s = vf
2.
x=0 +10.4(t) + 1/2(9.8)t2
x= 10.4t + 4.9t2
3.
t= -10.4+ {(Sqrt) ( 10.4^2-4(1)(4.9)}/ 2(1)
t= -10.4+ 9.42/2 ( using -10.4- 9.42/2 = -9.91s which doesn't seem realistic and gives a final answer of +500m)
t= -.49 time cannot be negative.
t= .49 s
2.
.49 and plug it back into
x=10.4t+ 4.9t^2
x= 6.27meters.
I'm given the answer as 5.47 m so I know I did something wrong or I used the wrong equations, however this question is in the Linear momentum section and the momentum is vertical? I don't know, please help :)