Question

A block of mass \[4\] kg is resting on a rough horizontal plane and is about to move when a horizontal force of $30$ N is applied on it. If $g = 10m/{s^2}$. Find the total contact force exerted by the plane on the block.

Answer 1

Hint: Force is the push and the pull on an object. Since its magnitude and direction both are important it is the vector quantity. Force is the product of mass into acceleration and is measured in kilogram into metre per Second Square and its SI (system international) unit is Newton. Here the total contact force is equal to the sum of all the forces acting on the block.

Complete step by step answer:
Let, the horizontal force be ${F_1} = 30N{\text{ }}.....{\text{(a)}}$
Let another force acting on the block be ${F_2} = m \times a$
Where, ” m” is the mass of the block and
“a” is the acceleration, here given that $a = g = 10m/{s^2}$
$m = 4kg$
Place the values,
$
{F_2} = 4 \times 10 \\
\implies {F_2} = 40N{\text{ }}......{\text{(b)}} \\
 $
The total contact force is $F = {F_1} + {F_2}$
Place values from the equations (a) and (b)
$
F = 30 + 40 \\
\therefore F = 70N \\
 $.

Hence, the required answer - the total contact force exerted by the plane on the block is $70N$

Note:
The above problem can be solved by another method as below-
The total force is equal to the sum of all the forces.
$
F = {F_1} + {F_2} \\
\implies F = mg + 30 \\
\implies F = 4(10) + 30 \\
\therefore F = 70N \\
$
Just implement correct formulas and basic concepts in these types of sums. Rest goes well just simplifying using the basic mathematical operations.