pulley lab inquiry

8/11/2019 Pulley Lab Inquiry

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DUE: THURSDAY (11/1/12) START OF CLASS

Name: ____________________ Period: ________________ Date: _______________

Purpose: To explore the mechanical advantage provided by different pulleysystems. You will be examining different pulley configurations to help youunderstand the concept of Mechanical Advantage (MA).

Materials: ring stand, pulleys, string, spring scale, weight, meter stick

Vocabulary: block and tackle, conservation of energy, efficiency, friction, inputforce, load, mechanical advantage, output force, pulley, pulley system, simplemachine, work

Prior Knowledge

A pulley is a wheel with a groove for a rope or cable. The image at left showsan example of a pulley system, also called a block and tackle.

Procedure:

#1: Single Fix Pulley

1. Use spring scale to determine the object’s mass (record in data

table).2. Setup pulley as shown.3. Use the spring scale to measure the force required to lift the weight

(record in data table)



(record in data table)

Pulley Activity

#3: Single Fixed, Single Moveable

1. Use spring scale to determine the object’s mass (record in datatable).

2. Setup pulley as shown.3. Use the spring scale to measure the force required to lift the weight

(record in data table).4. Count the number of strings pulling in the upward direction (record in

data table).5. Measure the height the object moves versus the distance the spring

scale moves (record in data table).6. Calculate AMA and IMA (record in data table).

#4: Double Fixed, Single Moveable

1. Use spring scale to determine the object’s mass (record in data table).2. Setup pulley as shown.3. Use the spring scale to measure the force required to lift the weight (record

in data table).4. Count the number of strings pulling in the upward direction (record in data

table).5. Measure the height the object moves versus the distance the spring scale

moves (record in data table). 6. Calculate AMA and IMA (record in data table).



Pulley Activity

Concept: The law of

conservation of energy states that in a closed system the total energyis constant. In other words, energy is neither created nor destroyed.

When using a simple machine, you use less force. What do you have to do more of inexchange?_________________________________________________________________

__________________________________________________________________________

How does a pul ley system demonstrate conservation of energy? __________________

__________________________________________________________________________ __________________________________________________________________________

Concept: A pulley is an example of a simple machine. Many simple machines are usefulbecause they allow the user to lift a heavy weight using less force than it would take to lift theweight directly. The mechanical advantage of the machine is a measure of this benefit.

Explain why the number of support ing ropes determines the mechanical advantage? __________________________________________________________________________ __________________________________________________________________________

Why can you count a section of rope you are pulling up on, but not a section you arepulling down on? _________________________________________________________

__________________________________________________________________________

How does fr ict ion affect the mechanical advantage of a pulley system? ____________



Pulley Activit y

Pulley Lab Data Sheet

Actual Mechanical Advantage (AMA) = (weight of the object) / (measured force required to lift the object)

Ideal Mechanical Advantage (IMA) = (Length of string pulled) / (Distance object lifted)

PulleyConfiguration

# StringsGoing Up

Object Weight(N)

ForceRequired to

Lift Weight (N) AMA

Height Lifted(cm)

Length ofString Pulled

(cm)IMA

#1. SingleFixed

#2. SingleMoveable

#3. SingleFixed, Single

Moveable

#4. Doublefixed,

SingleMoveable

#5. DoubleFixed, Double

Moveable

pulley lab inquiry

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