Asled is moving at a constant speed down a surface inclined at 45.0 with the horizontal and travels 30 meters in 4 seconds calculate the vertical velocity of the sled at the end of the 4 seconds

Because the speed of the sled is constant throughout this ordeal, we know that the instantaneous and average velocities are equal, and the velocity of the sled is

(negative because we're taking the downward direction to be negative)

The vertical component of this vector is given by

where is the angle made by the velocity vector with the positive -axis (taken to be the right direction). Here, , so

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray