Hello There!
The law of conservation of mass states that <em>Matter/substances/energy can not be created or destroyed, it can only be transferred from state to state.</em>
The guy below is wrong!
F=ma
Where force = mass x acceleration
We dont have acceleration, a= change in velocity divided by the time taken.
a = v (final velocity) - u (initial) / t
a us 8-0 (at rest means u was 0) / 20 = 0.4
Using F=ma
F= mass x acceleration
F= 4 x 0.4
F=1.6 N
According to Newton’s second law of motion:
F=ma
=80*0.5
=40N
