Relative Motion Using vectors to determine the speed of objects
Find the velocity of Train A 80 km/hr [E] Train B 110 km/hr [W] Train A relative to Train B (assume B is not moving) Train B relative to Train A
Find the relative velocity of each train Train A 80 km/hr [W] Train B 130 km/hr [W] 40 km apart How long for B to catch A?
What if the motions are at right angles? Wind 60 km/hr [S] Plane 120 km/hr [E] What is the velocity of the plane RELATIVE TO the ground?
Compensating for wind and current Wind 60 km/hr [S] Plane 120 km/hr At what angle should you head so that your plane heads “due east”? What will the “ground speed” be?
What if the vectors do not form a right triangle? Plane 120 km/hr [70 o ] Wind 60 km/hr [140 o ] How can we find the resulting velocity (both speed and direction) if the triangle is OBLIQUE?
Two Main Types of Problems <ul><li>1. Given the speed and direction of motion for an object, plus the speed and direction of the “medium” – wind, current – find the velocity of the object relative to the ground (speed and heading) </li></ul><ul><li>2. Calculate the angle at which an object in motion needs to head in order to compensate for the velocity of the medium; in other words, eliminate the change in your heading caused by the medium </li></ul>