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The impossible physics problem It\'s not 0.01 m. It\'s not 3.3 m. Any attempt to

ID: 1643086 • Letter: T

Question

The impossible physics problem

It's not 0.01 m. It's not 3.3 m. Any attempt to solve it thus far has been incorrect.

A 0.0270 kg bullet moving horizontally at 400 m/s embeds itself into an initially stationary 0.500 kg block. a) What is their velocity just after the collision? 20.49 (b) The bullet-embedded block slides 8.0 m on a horizontal surface with a 0.30 kinetic coefficient of friction. Now what is its velocity? m/s 19.3 m/s (c ) The bullet-embedded block now strikes and sticks to a stationary 2.00 kg block. How far does this combination travel before stopping?

Explanation / Answer

a) Initial momentum of system of system = 0.027*400 = 10.8 kg m/s

Let velocity after embedment be v

Total mass = 0.027+0.5 = 0.527kg

Final momentum of system = 0.527v

0.527v = 10.8

v= 10.8/0.527 = 20.49 m/s

b) coefficient of kinetic frition = 0.3

deceleration experienced by bullet-embedded block = 0.3*9.8 = 2.94 m/s2

u=20.49 m/s

let velocity after travelling 8 m be v

v2 = u2 + 2as

v2 = 20.492 +(2*2.94*8)

v = 19.3 m/s

c)Momentum of system before striking 2 kg block = 0.527*19.3 = 10.17 kg-m/s

Let velocity of system just after collision be u

Mass of system = 0.527+2 = 2.527kg

u=10.17/2.527 = 4.02m/s

Deceleration on system = 0.3*9.8 = 2.94 m/s2

Let distance travelled by system before stopping be s

s = 4.022/(2*2.94) = 2.75 m