What is the magnitude of the total momentum of the system consisting of the two balls?

Question

A baseball with mass 0.145 is moving in the +y - direction with a speed of 1.40 , and a tennis ball with mass 5.70×10−2 is moving in the -y - direction with a speed of 7.87 .

Answer 1

Momentum is the product of mass and velocity, and it is a vector, meaning it has direction (positive or negative in the y-direction, in this case). The baseball has momentum 0.145*1.4 = .203, and the tennis ball has momentum (5.70 x 10^-2)(-7.87) = -0.449. The sum of these momenta is -0.246, which has magnitude 0.246.

Answer 2

.652