# WORK DONE

Which of the following does not show work being done?
A
B
C
D
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Slide 1: Quizvraag
ScienceLower Secondary (Key Stage 3)

In deze les zitten 34 slides, met interactieve quizzen, tekstslides en 1 video.

Lesduur is: 50 min

## Onderdelen in deze les

Which of the following does not show work being done?
A
B
C
D

#### Slide 1 -Quizvraag

TOPIC: WORK, ENERGY AND MACHINES
In today's lesson you will learn to:
1. Describe what work is
2. Describe what simple machines are

#### Slide 2 -Tekstslide

WHAT IS WORK?
The energy transferred in order to move an object.
Work is not a form of energy - it is one of the ways in which energy can be transferred.

#### Slide 3 -Tekstslide

unit for work
unit for force
unit for distance

#### Slide 4 -Tekstslide

Work done (joule, J) = force (newton, N) × distance moved (metre, m)
W= F x d

We can rearrange the formula for work so we can calculate distance and force
Force = work done / distance
Distance = work done/ force

#### Slide 5 -Tekstslide

WORKED EXAMPLE 1
A boy throws a ball with a force of 70N over to his friend who is 3m away. Calculate the work done.

#### Slide 6 -Tekstslide

WORKED EXAMPLE 2
A girl does 500 J of work climbing a flight of stairs at a distance of 70m. Calculate her force.

A
10 W
B
10J
C
10 m
D
10N

A
20J
B
20m
C
20 N
D
20 W

#### Slide 10 -Quizvraag

Emily does work of 6 J, and pushes with
a force of 3 N, what distance does she
travel?

A
3N
B
3m
C
18 m
D
9J

#### Slide 11 -Quizvraag

A. An office worker has a weight of 750N. He climbs the stairs 20m to his desk. Calculate the work done
B. A mechanic applies a force of 120N to lever to lift a car, moving the lever through a distance of 0.4 m. Calculate the work done

#### Slide 13 -Tekstslide

What is a simple machine?
A simple machine reduces the force needed to do a job or increases the distance that something moves when a force is applied.

LEVERS

PULLEYS

GEARS

Examples of simple machines:

#### Slide 15 -Video

LEVERS
A simple machine consisting of a beam or rigid rod pivoted at a fixed hinge.

#### Slide 16 -Tekstslide

LEVERS
Levers are force multipliers – this means it allows us to apply forces more conveniently, or to increase the effort of a force.

The PIVOT – where the lever turns

The EFFORT – the force being applied to lever

The LOAD – the force which is being moved

#### Slide 18 -Tekstslide

Shen kicks a ball with a force of 90N to a distance of 4m across the MUGA. Calculate the amount of work Shen did.
A
360J
B
22.5J
C
94J

#### Slide 19 -Quizvraag

Which of the following is NOT an example of a lever?
A
B
C
D

#### Slide 20 -Quizvraag

What distance is moved if we have a 8N force and the work done is 90 J?

A
720J
B
11.25m
C
0.08m

#### Slide 21 -Quizvraag

LEVERS
Levers are force multipliers – this means it allows us to apply forces more conveniently, or to increase the effort of a force.

The PIVOT – where the lever turns

The EFFORT – the force being applied to lever

The LOAD – the force which is being moved

#### Slide 22 -Tekstslide

LEVERS
A wheel barrow is an example of a lever
EFFORT
PIVOT

#### Slide 23 -Tekstslide

A
A- effort; B - pivot; c - load
B
A - load; B - effort; C - pivot
C
A - effort; B - load; C - pivot

#### Slide 25 -Tekstslide

A
A- effort; B - pivot; c - load
B
A - load; B - effort; C - pivot
C
A - pivot; B - load; C -effort

#### Slide 26 -Quizvraag

A
A- effort; B - pivot; c - load
B
A - load; B - effort; C - pivot
C
A - pivot; B - load; C -effort

#### Slide 27 -Quizvraag

A
A- effort; B - pivot; c - load
B
A - load; B - effort; C - pivot
C
A - pivot; B - load; C -effort

#### Slide 28 -Quizvraag

A
A- effort; B - load; c - pivot
B
A - load; B - effort; C - pivot
C
A - pivot; B - load; C -effort