a) Calculate the acceleration of the object :

over the first 5 seconds.;
Acceleration is the rate of change of speed.
In the first 5 seconds the speed changes from 0 to 5m/s
=> 5m/s/5s = 1m/s/s. The speed increases by 1m/s every second.
between 10 and 13 seconds;
Between 10 and 13 seconds the speed changes from 5 to 10m/s, achange of 5m/s
=> 5m/s/3s = 1.67m/s/s. The speed increases by 1.67m/s every second.
between 5 and 10 seconds.
The acceleration is 0. The speed is constant, therefore no acceleration.

b) Calculate the magnitude of the deceleration.
Between 16 and 22 seconds the speed changes from 12m/s to 0m/s. Deceleration occurs.
=> 12m/s/6s = 2m/s/s. The speed decreases by 2m/s every second.

a) Calculate the acceleration of the object :

over the first 3 seconds.;
Acceleration is the rate of change of speed.
In the first 3 seconds the speed changes from 0 to 7m/s
=> 7m/s/3s = 2.33m/s/s. The speed increases by 2.33m/s every second.
between 12 and 16 seconds;
Acceleration is the rate of change of speed.
Between 12 and 16 seconds the speed changes from 5m/s to 10m/s
=> 5m/s/6s = 8.33m/s/s. The speed increases by 8.33m/s every second.
between 3 and 10 seconds.
Acceleration is the rate of change of speed.
Between 3 and 10 seconds the speed is constant. The acceleration is 0.

b) Calculate the magnitude of the first deceleration.
The first deceleration occurs between 10 and 12 seconds.
Between 10 and 12 seconds the speed changes from 7 to 5m/s
=> 2m/s/2s = 1m/s/s. The speed decreases by 1m/s every second.

c) Calculate the magnitude of the second deceleration.
The second deceleration occurs between 16 and 22 seconds.
Between 16 and 22 seconds the speed changes from 10 to 0m/s
=> 10m/s/6s = 1.67m/s/s. The speed decreases by 1.67m/s every second.