The net force needed to lift a full grocery sack uniformly is 32.115 N.
<h3>What is Net force?</h3>
When two or more forces are acting on the system of objects, then the to attain equilibrium, net force must be zero.
Given the weight of sack W = 210N and the acceleration a = 1.5m/s².
The mass of the sack will be
m = Weight / acceleration due to gravity
m = 210 N/9.81 m/s²
m = 21.41 kg
Using Newton's second law, the net force will be
F = mass x acceleration
F= 21.41 x 1.5
F = 32.115 N
Thus, the net force is 32.115 N.
Learn more about net force.
brainly.com/question/18031889
#SPJ1
Refer to the 2th Law of Newton
F = m. a
F = 15 x 2.8 = 42 N
The sun provides light and energy for plants to live and we need plants to breathe
I hope this helps you
<h3><u>Mass of an object affect the outcome of unbalanced forces:</u></h3>
Newton’s second law of motion deals with the result of motion of an object when unbalanced forces are applied. The second law of motion establish the relationship between mass, acceleration and unbalanced forces of the object. The below points explains the relation between unbalanced forces acting on mass of the object. The acceleration of object would be higher when the unbalanced force is higher.
The equation for the unbalanced force is,

For Example: Two masses of 500 kg and 1 kg is applied with same unbalanced forces. The change in motion of 500 kg would be very much less than the change in motion of 1 kg.
Mass and energy are inter convertible.As per Einsteins mass and energy relations i.e
,some amount of energy is lost that is converted into energy .
In our day to day life ,generally mass is lost and energy is formed. In a ideal assumption we subtract the mass of earlier one from the later one which indirectly denotes that some amount of mass is lost and energy is released .There is also endothermic reactions where energy is needed which does not mean mass is added.Here simply energy is needed to initiate the reactions.
So instead of subtracting the smaller value from lager we subtract the initial value from final as the latter one can explain a physical phenomenon in a better way.we can get some in formation from it.