Problem with distance in relation to acceleration.

[BeeGeeks]

Homework Statement
A 1200 kg car is at a red light on a horizontal road. When the road turns to green, (t0) he starts accelerating and reaches 14 m/s in 7 seconds. He then continues at a constant speed for 10 seconds, then brakes with a -3.5 m/s^2 acceleration.

All accelerations are assumed to be constant.

a) Calculate the amount of time he spends decelerating. (What I found through graphing : 4 seconds)

b) Graph the speed in relation to time starting with t0. (Done successfully)

c) Calculate the average speed in both the acceleration and deceleration phase. (7 m/s)<- this seems weird to me)

d) Calculate the total distance between the start of the acceleration until the final stop.

I'm having trouble with point d).

The problem

I don't understand how we can calculate a distance while the object is under acceleration. I can't wrap my head around it. Is there an equation I don't know about? Or am I overcomplicating things and it's just ( for this problem) an additional 2 meters per second during the acceleration phase, then 10 seconds of adding 14 m per second and then decreasing the number you add to your total by 3 every second starting by 14 during your deceleration? is it that obvious?

Thanks in advance!

 

[Doc Al]

I don't understand how we can calculate a distance while the object is under acceleration.

Why not? It's moving isn't it? What's the average speed during each segment of the motion? Use that to find the distance traveled.

 

[BeeGeeks]

Why not? It's moving isn't it? What's the average speed during each segment of the motion? Use that to find the distance traveled.

Thanks!

 

[CWatters]

Well worth memorising the four/five basic equations of motion. See "SUVAT equations" down here..

http://en.wikipedia.org/wiki/Equations_of_motion