Calculating Motion with Constant Acceleration: Solving for Time and Distance

[cal.queen92]

Homework Statement

A body moving with constant acceleration in a straight line covers the distance between two points 60.0m apart in 5.0s. Its velocity as it passes the second point is 15.0m/s.

a) What is:
i) The acceleration of the object?
ii) Its initial velocity?

b) Assuming constant acceleration how long had it been in motion before it reached the first point?

c) How far is it from the starting point when it passes the second of the two points which are 60.0m apart?

Homework Equations

constant acceleration equations

The Attempt at a Solution

I have solved part a) where the acceleration = 1.2 m/s^2 and the initial velocity = 9.0m/s

Now I am having trouble with part B. (which is making part C tricky)

What I understand is that for part B the final velocity would be the the initial velocity from part A (after drawing a sketch) and the acceleration is constant. So I have two known quantities:

V(final) = 9.0 m/s
a = 1.2 m/s^2

I am missing a quantity to be able to solve for time, but where am I missing it?

The only thing I can think of is that is the initial velocity is 0.0 m/s , but I'm not sure this is logical.

Any idea?
Thanks!

 

[Delphi51]

Yes, zero initial velocity. It says, "how long had it been in motion", which implies we are timing from the time it started moving.

 

[cal.queen92]

Fantastic! Thank you.