Q: A projectile flies with a velocity of 750 km per hour at a 300 angle south of east:
What is the magnitude of the eastward component of motion?
A: The projectile is moving both eastward and south simultaneously. The eastward component of motion is determined by using an appropriate trigonometric function that relates the 300 angle with the sides of an imaginary right triangle:
The adjacent ( green ) side of the triangle is of interest to us, so we use the cosine function to solve the problem:
cos θ = adj/hyp
hyp cos θ = adj
( 750 km/h )( cos 300 ) = 650 km/h
RENAISSANCE PHYSICS 