
A boy is pushing hard on a wall. Is he doing work?
(A) No
(B) Can’t say
(C) May have done some work
(D) Yes
Answer
123.3k+ views
Hint: We will see that when a boy pushes a wall, he is applying force on the wall. We see that the wall shows no displacement. Work is given as the product of the forces and the displacement in the same direction. Hence the work done is zero.
Complete step by step answer:
Work done:
Work is said to be done when force is applied on an object and it gets displaced from its initial position. SI unit of work is Joules.
1 Joule is defined as 1 newton force is applied on an object and it gets displaced by 1 m distance.
$\Rightarrow$ $1joule = 1\,Newton\,metres \Rightarrow 1\,J = 1\,Nm$
Mathematically;
$\Rightarrow$ $W = F\,s\,\cos \theta $ … (1)
W = work done
F = applied force
s = distance covered by an object
$\theta $= angle between applied force and object displacement
In this case when boy pushes on the wall, it shows no displacement
S = 0 … (2)
Using equation (2) in (1), we get
$W = F.0 \Rightarrow W = 0$
This represents that no work is done when force is applied on a wall.
Secondly, the wall does not get displaced from its initial position. So,
S = 0
Thus, the correct option is A. He is not doing any work.
Note:
The boy still gets tired even when the total mechanical work is zero. This means that the boy is using energy. To clarify this apparent paradox lets understand and Note: that energy needn’t be only converted to work; it can also get converted to other types of energies like heat, light, sound etc. IN our case the boy gets tired trying to oppose the rigidity of the wall. Theoretically the boy is compressing the wall. However, the wall’s tensile strength is too high hence the negligible amount of compression that the boy would have caused goes unnoticed. The boy’s energy is also lost in the form of heat due to which we would practically see him sweating
Complete step by step answer:
Work done:
Work is said to be done when force is applied on an object and it gets displaced from its initial position. SI unit of work is Joules.
1 Joule is defined as 1 newton force is applied on an object and it gets displaced by 1 m distance.
$\Rightarrow$ $1joule = 1\,Newton\,metres \Rightarrow 1\,J = 1\,Nm$
Mathematically;
$\Rightarrow$ $W = F\,s\,\cos \theta $ … (1)
W = work done
F = applied force
s = distance covered by an object
$\theta $= angle between applied force and object displacement
In this case when boy pushes on the wall, it shows no displacement
S = 0 … (2)
Using equation (2) in (1), we get
$W = F.0 \Rightarrow W = 0$
This represents that no work is done when force is applied on a wall.
Secondly, the wall does not get displaced from its initial position. So,
S = 0
Thus, the correct option is A. He is not doing any work.
Note:
The boy still gets tired even when the total mechanical work is zero. This means that the boy is using energy. To clarify this apparent paradox lets understand and Note: that energy needn’t be only converted to work; it can also get converted to other types of energies like heat, light, sound etc. IN our case the boy gets tired trying to oppose the rigidity of the wall. Theoretically the boy is compressing the wall. However, the wall’s tensile strength is too high hence the negligible amount of compression that the boy would have caused goes unnoticed. The boy’s energy is also lost in the form of heat due to which we would practically see him sweating
Recently Updated Pages
The ratio of the diameters of two metallic rods of class 11 physics JEE_Main

What is the difference between Conduction and conv class 11 physics JEE_Main

Mark the correct statements about the friction between class 11 physics JEE_Main

Find the acceleration of the wedge towards the right class 11 physics JEE_Main

A standing wave is formed by the superposition of two class 11 physics JEE_Main

Derive an expression for work done by the gas in an class 11 physics JEE_Main

Trending doubts
JEE Main 2025 Session 2: Application Form (Out), Exam Dates (Released), Eligibility & More

JEE Main Login 2045: Step-by-Step Instructions and Details

Class 11 JEE Main Physics Mock Test 2025

JEE Main Exam Marking Scheme: Detailed Breakdown of Marks and Negative Marking

JEE Main 2023 January 24 Shift 2 Question Paper with Answer Keys & Solutions

JEE Main 2025: Conversion of Galvanometer Into Ammeter And Voltmeter in Physics

Other Pages
JEE Advanced Marks vs Ranks 2025: Understanding Category-wise Qualifying Marks and Previous Year Cut-offs

NCERT Solutions for Class 11 Physics Chapter 1 Units and Measurements

NCERT Solutions for Class 11 Physics Chapter 9 Mechanical Properties of Fluids

Units and Measurements Class 11 Notes: CBSE Physics Chapter 1

JEE Advanced 2025: Dates, Registration, Syllabus, Eligibility Criteria and More

NCERT Solutions for Class 11 Physics Chapter 2 Motion In A Straight Line
