I'm taking Physics for the first time in three years by correspondence... I'm struggling with a few questions, so any help would be greatly appreciated! I promise there isn't actually THAT many questions here. For the most part I have the answers to the parts a and b. Thanks in advance for any help! 1. You head across the Battle River in your boat with a velocity of 8.0 m/s, south. The river is flowing at 2.8 m/s, east. a. Make a sketch indicating both velocity vectors. Show the resultant vector. I've done this and I'm faily certain what I have is correct. b. Determine the magnitude and direction of the resultant velocity vector. I got an answer of 8.5 m/s (which, again, I'm fairly certain is correct) what I don't get, is how to find the direction of the resultant velocity vector. I tried it and got a rather bizarre answer. c. Assume that you and your boat have a total mass of 192 kg. Calculate the magnitude and direction of the momentum of you and your boat as you cross the river. I calculated the momentum to be 1632 kg*m/s. Again, that seemed pretty straight forward to me. I'm lost on the direction again though. I believe it would be the same as the direction of the resultant vector? 2. A railway car with a mass of 8.30 x 10^4 kg is moving west at 6.25 m/s when it collides with another car with a mass of 9.64 x 10^4 kg moving east at 7.00 m/s. The two freight cars join together at impact. a. What is the common velocity of the two cars after they join together? I got an answer of 0.870 m/s, East. b. Calculate the magnitude of the impulse provided to each freight car in this collision. I used mvf-mvi... I got the same answer of 5.91 x 10^5 for both cars... does that seem right? c. Now calculate the percent loss of kinetic energy. I used % Ek lost = ((deltaEk)/(Ekinitial))... I'm not sure if that's correct though. 3. Sara's favourite game is marbles. Her favourite marble is a large steel marble with a mass of 32 g. She shoots it with a speed of 24 cm/s directly at a staionary, smaller glass marble with a mass of 15 g. After the collision, the glass marble moves ahead with a speed of 30 cm/s. a. Determine the resulting speed of the steel marble. I got an answer of 0.23 m/s. Again, I'm not positive that's correct. b. If this collision had been perfectly elastic, determine the resulting velocities of both the glass and the steel marbles. I don't really know how to do this. I understand that elastic means there isn't a change in the kinetic energy, but that's about all I understand.