Two billiard balls of equal mass move at right angles and meet at the origin of a xy coordinate system. One is moving upward along the y axis at 2.1 m/s and the other is moving to the right along the x-axis with a speed of 3.8 m/s. After the elastic collision, the second ball is moving along the positive y-axis. What is the final direction of the first ball, and what are their two speeds?

Which of the following is considered to be a vector?               a.  temperature    b.  velocity    c.  time    d.  mass

What sort of waves exhibit the doppler effect?

It's a snowy day and you're pulling a friend along a level road on a sled. you've both been taking physics, so she asks what you think the coefficient of friction between the sled and the snow is. you've been walking at a steady 1.5m/s, and the rope pulls up on the sled at a 32 ∘ angle. you estimate that the mass of the sled, with your friend on it, is 65 kg and that you're pulling with a force of 80 n .