Villa Maria Techno Farm Pedagogical Activity Guide

Title Simple Machines in the Garden

Course Secondary 2 Science and Technology

Summary

This activity involves identifying the types of simple machines found in common garden tools.

Curriculum Connections:

ST: Material World - Understand how simple machines can be used to make life easier.

Materials Required

1) Supporting Documents - Simple Machines Activity Document (Appendix 1) - Simple Machines Theory (Appendix 2

2) Materials • Hand trowels • Shovels • 20 L Buckets • Wheelbarrow

Procedure (see Simple Machines Activity Document in Appendix 1 for detailed procedure)

This pedagogical activity guide was produced with the financial support of:

Appendix 1 - Simple Machines Activity Document

Instructions to teacher :

This activity takes place outdoors in an area where digging is permitted. Once the activity is over, the dug-up soil may be replaced. It is important not to leave uncovered holes or pits in the ground as this can constitute a safety hazard.

Based on the local soil conditions, time available and the physical abilities of the students, the teacher must determine in advance: 1) How much soil must be dug up for the “Digging” activity 2) How much soil will be carried in the “Carrying” activity 3) How far the soil must be carried in the “Carrying” activity

Part 1 - Experimentation Activity Materials Procedure Observations Digging Hand Trowel, The following tasks must be Shovel performed by a single student

1) Use a hand trowel to dig up enough Which tool was easier to use, the trowel earth to fill a 20 L bucket to a or the shovel? designated level. The trowel must be

used with 1 hand. Make a hypothesis to explain the

difference. 2) Use a shovel to dig up enough earth to fill a 20 L bucket to a designated level. The shovel must be used with 2 hands. Carrying 20 L Bucket, The following tasks must be Wheelbarrow performed by a single student

Which method made it easier to 1) Carry two 20 L buckets filled with transport the soil, the buckets or the soil a given distance (as determined wheelbarrow? by the teacher)

Make a hypothesis to explain the 2) Fill a wheelbarrow with soil from difference. two 20 L buckets. Push the wheelbarrow a given distance (as determined by the teacher)

Part 2 – Analysis.

1) Make scale drawings of each pair of tools that were used in the 2 activities. 2) On the sketch, indicate the elements of simple machines that were present in each tool. 3) Calculate the mechanical advantage of each tool using the scale drawings. 4) Compare the results of your analysis to your observations. 5) Make a conclusion based on your analysis and observations.

Appendix 2 - Simple Machines Theory Document

1) Trowel vs. Shovel

All types of shovels (including 1-handed trowels) are compound machines consisting of a of a wedge and a class 3 lever.

The wedge is the blade of the shovel which transforms the force directed along the handle of the shovel by the worker into forces which push outwards from the blade surfaces allowing the head of the shovel to cut into the soil.

The shovel is a lever when it is used to lift soil out of the ground. The resistance load is the soil on the head of the shovel.

In the case of a 2-handed shovel the hand closer to the head of the shovel is the fulcrum, and the hand on the handle exerts the effort force.

In the case of a 1-handed shovel (trowel) the forward edge of the hand (thumb and forefinger) closer to the head of the shovel is the fulcrum, and the rearward edge of the hand (palm heel near the pinky) exerts the effort force. Therefore, the lever arm of the trowel is much smaller than of a 2-handed shovel.

2) Bucket vs. Wheelbarrow a) Bucket

A bucket is not a simple machine. The weight of the resistance load (i.e. the soil in the bucket) is entirely supported by the worker.

Therefore, the mechanical advantage of a bucket is 1.

In an ideal situation, no mechanical work is performed when carrying a load along a horizontal surface. However, due to friction, unevenness in the surface and biomechanical considerations, in practical situations energy must be expended to carry loads along horizontal surfaces.

b) Wheelbarrow

Wheelbarrows are compound machines consisting of 3 simple machines: a lever, wheel and axle, and an inclined plane.

The wheelbarrow makes use of a class 2 levers: the resistance load is between the fulcrum (wheel) and the location of the effort force (hand grip).

The wheelbarrow's wheel and axle allow it move with reduced friction.

Since a wheelbarrow used with a forward pitch (tilt) it is it considered to make use of an inclined plane. This comes into play only when dumping soil onto the ground.