 In this video, we're going to work out lots of the information you might want to know about an object undergoing projectile motion. These example videos will be much more useful to you if you pause and have a go yourself before watching how it's done. A dolphin jumps out of the water. If the dolphin jumps at a speed of 5 meters per second and at an angle of 60 degrees to the horizontal, A, what is the initial vertical velocity of the dolphin? B, what is the initial horizontal velocity of the dolphin? C, at what distance does the dolphin re-enter the water? D, at what time does the dolphin re-enter the water? And E, what is the maximum height reached by the dolphin? We'll also look at a couple of questions about finding an unknown angle using projectile motion as follows. What angle to the horizontal should the dolphin jump? A, to reach the height of 1.1 meters, and B, to re-enter the water at the maximum distance. Firstly, we're going to calculate the initial vertical and horizontal velocities. We can draw a component diagram of the velocity, and we can see that we can calculate Vix and Viy from trigonometry. Now we know that initial velocity Viy is 5 meters per second, and we know that theta, the angle to the horizontal, is 60 degrees. So Vix must be 5 on 2 meters per second, and Viy must be 5 times root 3 on 2 meters per second. I've left it as an improper fraction, but you could also put sign of 60 degrees or cos of 60 degrees into your calculator and get a decimal number.