Calculate the force needed to accelerate.

Question

Calculate the force needed to accelerate an 80000 tonne oil tanker from rest to 14ms^-1 in six minutes. 1 tonne = 1000 kg.

Answer 1

This problem is fairly straightforward. The trick is to make sure all the units are kept track of.

The term "tonne" is an abbreviation for metric ton, which is 1000kg.

We want to know the Force required to accelerate an object, so we'll use Newtons 2nd law. The force acting on an object is equal to the mass of the object times the acceleration (F=ma).

The mass is 80,000 tonne, but we need that in kilograms (kg). There's 1000 kg in each tonne.

m = (80,000 tonne)(1000 kg/tonne) = 80,000,000 kg

The acceleration is the change in velocity divided by the change in time.

We accelerate up to 14m/s in 6 minutes. 6 minutes = 360 seconds

a=v/t = (14m/s)/(360s)=(7/180)m/s/s I'll leave this as a fraction to reduce the uncertainty in the calculation.

We can put that all together into the equation F=ma = (80,000,000kg)(7/180)(m/s/s) = 3,111,111 Newtons

If we were to take significant digits into account, we only know the precision to one digit;

F = 3,000,000 Newtons.