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Homework Help: Need Help with Kinematics

  1. Nov 8, 2006 #1
    Hey, everyone I am new to this site... I found it because I am despreate need of help in physics. I just started it this year and am having extreme difficulty. My average in my advanced math class is 87% but I just can't seem to get physics. I don't like to blame teachers but to be honest he is not very helpful or easy to understand. I have the answers for the current problems because he gave them to us but I need a lot of help understanding the process.


    1. A car parked 40Km east of a train station travels westwards for 4 hours. If after 4 hours the car is observed to be 100Km west of the station, determine the average velocity of the car

    2. A skier accelerates down a hill from 2.5 m/s to 8.9 m/s in 3.4s. Determine the distance the skier tavelled during his acceleration.

    3. A truck, travelling at 22 m/s, accelerates constantly while going through a tunnel. If the truck's acceleration is 4.0 m/s^2 and it exits the tunnel with a velocity of 35 m/s, determine the length of the tunnel

    4. A pony running at 3.0 m/s, accelerates uniformly at 3 m/s^2 for 5 s. What is the displacement during the second second

    Any help would be greatly appreciated, and there is more stuff to come...
  2. jcsd
  3. Nov 8, 2006 #2
    1. You know that the average velocity will be the product of the total distance traveled and the time. You don't have to worry about displacement issues because he travels in only one direction.

    2. A kinematic equation will solve this. Advanced math probably doesn't mean calculus, so you have probably been given kinematic equations so solve algebraically.

    3. Again, you could use a kinematic equation.

    4. This question confuses me, but it seems like you are supposed to find how far it goes after two seconds and ignore the other three seconds.
  4. Nov 9, 2006 #3

    thx a lot... it's still hard for me and I don't know why... just one problem I need help with this time

    5. A projectile is launched straight up at 250m/s. Some time later it is observed to be coming straight down at at 150m/s. What is the lapse time between observations. (ignore frictional losses)

    and Yes you were right, I didn't start calculus yet... i'm in Grade 11 high school.. however in Quebec that's the year we graduate followed by going to cegep which is like 2-3 years (depending on program) then it's university, so I am starting Calculus next year and everything in physics is done algebraicilly (sp??) although I am good at algebra itself... it's the whole background stuff I have problems with in physics before it becomes math.
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