An 8.0-g bullet is fired into a 4.0-kg block that is initially at rest on a frictionless horizontal surface. The bullet remains lodged in the block. The block moves into an ideal massless spring and compresses it by 8.5 cm. The spring constant k The spring constant of he spring is 2400 N/m. The initial velocity of the bullet is closest to.

12,750m/s

Explanation:

The change of momentum of the bodies = Force that causes the spring to extend

momentum = mass × velocity

Force on the spring = 1/2ke²

K is the spring constant

e is the extension

Since momentum = mass m × velocity v

The equation becomes

m1u1+m2u2 = 1/2ke²

m1 and u1 are the masses of the bullet and block respectively.

u1 and u2 are the velocities of bullet and block respectively

Given m1 = 8.0g = 0.008kg

u1= ?

m2 =4kg

u2 = 0m/s (block initially at rest)

Substituting this values in the formula

0.008u1+4(0) = 1/2× 2400 × 0.085

0.008u1 =102

u1 = 102/0.008

u1 = 12,750m/s

so easy. just google the electromagnetic waves and it’ll pop up.