Use the definition of acceleration:
Acceleration = (change of velocity) divided by (time for the change)
The graph says:
Change of velocity = -6 m/s
Time for the change = 3 sec
So Acceleration = (-6m/s) / (3 s)
That's -6/3 m/s•s
or
-2 m/s^2
Answer:

Explanation:
Given that,
The initial speed of a car, u = 0
Time, t = 18 s
Distance, d = 390 m
We need to find the acceleration of the car. Let it is a. Using the second equation of motion to find it.

or

So, the acceleration of the car is
.
When someone stands against a locker and is does not moving at all, then there will be no displacement and since displacement = 0
Work done also becomes equal to zero.
Work done is usually defined as change in energy. Since the work done is zero there has been no energy used.
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