Recent content by fphysicsclass

And I ended up on 2 getting 4.36 seconds. Did anyone else get this?

I started number 2 using knowledge from 1. I set 2 displacement equations equal to each other. Was I wrong to say that: (1/2)(2.5)(t^2)=4.2t ?? I will add a second at the end to make up for the lost time.

I'm lost again. I was trying to find distance when I should have been trying to find time. Any tips for starting number 2? I already drew a v-t graph, making sure my constant a was a straight line.

Thank God you can type in "1/170 hours to seconds" and get a perfect conversion.

Haha, yes it is. That is why I did double check. I submitted my answer for that one, and got it right. It was 21.2 seconds, and 0.53 km. Now for #2!

Which actually should be moved over a couple decimal places and be 21.2 seconds.

170 is in kmh. I converted my answer to seconds because that is what the answer form asked for. I made sure to include it in my original post.

I probably should find the rel. vel. of the car. If I did, would I be right to use 170t = 1 to solve for time? I got 0.02 s.

On #1, how should I start out on the opposite directions. I know that the train will be traveling @ -80 kmh, and the car, +90 kmh. I don't know what the relative velocity of the train would be. Maybe -170 kmh?

Ok. So for 1, I got 6 min and 9 km. Now I need to do part b. Also, I will be starting 2 after that.

azizlwl - I will try your method, and I think I messed up in drawing the x-t graph for a = c. I drew the v as exponentially increasing. I got it confused with the x-t graph. You know how it is, first day of AP Phys. A little lost. Haven't taken phys in 2 years. Will keep you updated.

For 1, I did 10t = 1; t = 6 min. Does anyone (dis)agree, and can help with 1 and/or 2?

I don't know. Can anyone help? this is frustrating, and I almost have to turn it in online. I tried graphing the x-t graph, and can't make sense of it. I understand that one must equate 2 equations - that is how you find the intersection. But my answer is always wrong. I just want some help. Thanks.

ehh. I can't even figure out the first one. So, I have 90t + 1 = ? I don't know where to go from there. Oh wait. 90t+1 = delta x?

Also, it wouldn't make sense for the first one to draw a v-t graph because v doesn't tell you anything about position. Should I instead drawn a x-t graph?