8.26 You and your friends are doing physics experiments on a frozen pond that se

Question

8.26

You and your friends are doing physics experiments on a frozen pond that serves as a frictionless, horizontal surface. Sam, with mass 71.0kg , is given a push and slides eastward. Abigail, with mass 51.0kg , is sent sliding northward. They collide, and after the collision Sam is moving at 32.0? north of east with a speed of 5.20m/s and Abigail is moving at 22.0? south of east with a speed of 9.80m/s .

A. What was the speed of each person before the collision? Sam's speed:=

B.Abigail's speed:

C By how much did the total kinetic energy of the two people decrease during the collision?

Explanation / Answer

conservation of momentum along X and Y directions

X direction

m1u1 + m2u2 = m1v1 + m2v2

71*u1 = 71*5.2*cos32 + 51*9.8*cos22

71*u1 = 313.1 + 463.406

u1 = 10.9367 m/s

sam's speed = 10.9367 m/s

b) Y direction

m1u1 + m2u2 = m1v1 + m2v2

51*u2 = 71*5.2*sin32 -51*9.8*sin22

51*u1 = 195.646 - 187.228

u2 = 0.165 m/s

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