The document provides a physics lesson on the concept of work done. It defines work as the product of the applied force and the distance moved by an object. It gives the general formula for calculating work as W=Fdcosθ, where θ is the angle between the force and displacement. Maximum work is done when θ=0° and force is parallel to displacement. Zero work is done when the force is perpendicular to displacement (θ=90°) or there is no displacement (d=0). An example calculation of work done by lifting a load is provided. Practical problems applying the concept of work are given at the end.

1. PHYSICS LESSON
SUBJECT: PHYSIC
CLASS LEVEL : FORM ONE
TOPIC :
CONCEPT OF WORK DONE
YOUR TEACHER:
MWEMA ISSA MWEMA

2. CONCEPT OF WORK
In order to do work three things are
needed
ENERGY APPLIED FORCE DISTANCE MOVED BY A BODY
WORK DONE

3. Work can be defined as a product of the force
applied on body and the distance moved by
body
𝑤. 𝑑 = 𝑭(𝑁) × 𝑑(𝑚)
Where force 𝑭 = 𝐹 cos 𝜃
𝑤. 𝑑 = 𝐹 𝑐𝑜𝑠 𝜃 × 𝑑
Where 𝜃 direction of applied force
𝒘. 𝒅 = 𝑭 𝒅 𝒄𝒐𝒔 𝜽
This is general formula of work done

4. Maximum and Zero work done
Maximum work done
𝒘. 𝒅 = 𝑭 𝒅 𝒄𝒐𝒔 𝜽
Work done will be maximum when force acts on
angle θ = 0
w. d = F d cos θ = Fd cos 0
cos 0 = 1
Since the maximum work done calculated by
formula
𝒘. 𝒅 = 𝑭𝒅
the work done is measured in Nm or Joules

6. • Zero work done, it occurred under two
conditions
𝒘. 𝒅 = 𝑭 𝒅 𝒄𝒐𝒔 𝜽
• If force act on a body is perpendicular to
motion of an object θ = 90 ,
𝑤𝑑 = 𝐹 𝑑 𝑐𝑜𝑠 90 = 𝟎 𝑱𝒐𝒖𝒍𝒆𝑠
force
displacement

7. • When force applied on object, and it remain
at its rest position( no displacement) i.e.
when 𝒅 = 𝟎 𝒎
• 𝐰. 𝐝 = 𝐅 × 𝟎 = 𝟎 𝐉𝐨𝐮𝐥𝐞𝐬

8. WORKED EXAMPLE
A man lifts a heavy load with a force of 200N, Calculate
maximum work done if he rise it to 1.5 m.
Given data
Applied force 𝐅 = 𝟐𝟎𝟎 𝐍
Displacement in which load lifted 𝐝 = 𝟏. 𝟓 𝐦
Work done = ?
Solution
From the formula 𝐰𝐨𝐫𝐤 = 𝐅 × 𝐝
𝐰𝐨𝐫𝐤 = 𝟐𝟎𝟎𝐍 × 𝟏. 𝟓𝐦
work done = 30 Joules

9. Practical problems
1. Calculate the work done when a 10kg object
is lifted to height of 5m above the ground.
2. If your mass is 45 kg , how much work would
you do in climbing a ladder that is 10m height.
3. Let an object is dropped and falls to the
ground surface.
a. Is a work done while it falling ?
b. If so, what the force did work ?
c. Was work done on or by the object ?
Hint 𝐅 = 𝐦𝒈 and 𝒈 =10N/kg

10. If will be there any contradiction or miss
understand about ,please contact with me on
Gmail account isamwema@gmail.com or phone
number +255776863549