Question

A man of mass $50\,kg$ carries a bag of weight $40\,N$ on his shoulder. The force with which the floor pushes up his feet will be
A. $882\,N$
B. $530\,N$
C. $90\,N$
D. $600\,N$

Answer 1

Hint:To answer this question, we first need to understand what is mass and weight. A measure of an object's inertial property, or the amount of matter it contains, is its mass. The force exerted on an object by gravity, or the force required to support it, is measured by its weight.

Complete step by step answer:
Weight: Weight is defined as the force exerted on a body by gravity, according to the most common concept used in introductory physics textbooks. This is commonly expressed as $W = mg$, where $W$ is the weight, $m$ is the object's mass, and $g$ is the gravitational acceleration.

Mass: In physics, mass is a numerical measure of inertia, which is a basic property of all matter. It is, in essence, a body of matter's resistance to a change in speed or location caused by the application of a force. The smaller the shift caused by an applied force, the greater the mass of the body.

Assume that the force with which the floor pushes up his feet is $R$. Therefore, the total force with which the floor pushes up his feet is the sum of the weight applied by bag and weight of the man.
$R$= weight of the man + weight of the bag
$\Rightarrow R = (50 \times 9.8) + 40$ (where g is the acceleration due to gravity ie.9.8)
$\therefore R = 530\,N$

Hence, the correct answer is option B.

Note:A substance's mass is the amount of matter it contains. The net force on a falling object, or its gravitational force, is its weight. Gravitational acceleration is experienced by the object. All dropping objects on Earth experience some upward pressure from the air, but they can never completely be in free fall.