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Homework Statement
The accelerationtime graph above is drawn for a body which starts from rest and moves in a straight line. The body is of mass 10 kg.
Use the graph to find:
(a) the average distance travelled in 15 s,
(b) the average force acting over the whole 15 s period.
Answers: (a) 125 m, (b) 6.66667 N / 6.2/3 N
Homework Equations

The Attempt at a Solution
(a) v = 2 m s^{2} * 5 s = 10 m s
s = 10 m s * 5 s = 50 m
or
s (t) = 1/2 a t^{2}
s = 1/2 * 2 * 15^{2}  1/2 * 2 * 10^{2} = 125 m
In both cases I assumed that it's 5 and not 0 in the Time/s graph.
But I am completely not sure about the solutions and also if the acceleration was only 5 seconds why can't I get 125 m using just 1/2 * 2 * 5^{2} = 25 m...
Any suggestions please? Thank you in advance.