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January 30, 2015

January 30, 2015

Posted by **Megan** on Tuesday, October 16, 2012 at 4:16pm.

- Physics- Elena please help! -
**Elena**, Wednesday, October 17, 2012 at 3:48amLaw of conservation of energy

KE =PE

(m1+m2) •u²/2 =kx²/2

u=sqrt{kx²/(m1+m2)}=.....

Law of conservation og linear momentum

m1v + 0= (m1+m2)u

v=(m1+m2)u/m1 =....

- Physics -
**Richmond**, Tuesday, January 22, 2013 at 8:12pmWork backwards, because you cannot solve it forwards since there are two unknowns.

(a) Start with the energy transferred to the compressed spring. The block transfers energy to the spring, that's why it compresses.

Ek = Ee

mv^2 = kx^2 (halves cancel)

v = sqrt[(kx^2)/m]

v = .310 m/s

(b) Momentum is conserved. The momentum before is the momentum of the bullet. After, it is the combined mass of bullet and block.

Let u be the initial velocity of bullet

mu = (m1+m2)v

u = 1.63 m/s

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