.11 Red Pocket? ??2:17 @ 1 o 78%-0. on.masteringphysics.com c Homework 9 Item 12

Question

.11 Red Pocket? ??2:17 @ 1 o 78%-0. on.masteringphysics.com c Homework 9 Item 12 12 f A firecracker in a coconut blows the coconut into three pieces. Two pieces of equal mass fly off south and west, perpendicular to each other, at 20 m/s. The third piece has twice the mass as the other two. Part A What is the speed of the third piece? Express your answer using two significant figures. . Part B What is the direction of the third piece? Give the direction as an angle east of north Express your answer using two significant figures Returm to Assin Provide Feedback

Explanation / Answer

Using momentum conservation

In x-direction

Pix = Pfx

Pix = 0, since initially coconut was at rest, So

Pfx = m1*v1x + m2*v2x + m3*v3x = 0

m1 = m2 = m, & m3 = 2m

v1x = 0 m/sec

v2x = -20 m/sec

m*0 + m*(-20) + 2m*v3x = 0

v3x = 10 m/sec

In y-direction

Piy = Pfy

Piy = 0, since initially coconut was at rest, So

Pfy = m1*v1y + m2*v2y + m3*v3y = 0

m1 = m2 = m, & m3 = 2m

v1y = -20 m/sec

v2y = 0 m/sec

m*(-20) + m*0 + 2m*v3y = 0

v3y = 10 m/sec

So speed of third piece will be

v3 = v3x + v3y

|v3| = sqrt (v3x^2 + v3y^2)

|v3| = sqrt (10^2 + 10^2) = 14.14 m/sec = 14 m/sec

Direction = arctan (10/10) = 45 deg Counter-clockwise to east = 45 deg east of north

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