So your finding acceleration first which is 30m/s divides by 6 seconds equals 5m/s^s and then multiply that by 1,400 kg and you have net force which is 7,000N
You faded out there before asking your question.
Here's some info that might be of interest:
Torque = (force) x (distance from the pivot) = (10 n) x (0.9 m) = 9 newton-meters
Answer:
Part 1: 0.3789
Part 2: 746 J
Part 3: 2.162 kW
Explanation:
Part 1:
Eff= 
Eff= 0.378873 ≈ 0/3789
Part 2:
W= 0.3789(1969)
W= 746 J
Part 3:

Power= 2162.3188 Watts
2162.3188 W-----> 2.162 kW
There are 2.1077x10^24 atoms of sulfur in 3.50 mols of sulfur.