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To See How The Force Required To

Pull A Shoe Depends On The Mass Of The Shoe Essay, Research Paper

To See How The Force Required

To Pull A Shoe Depends On The Mass Of The Shoe ObjectiveAs part of our Physics course-work we were asked to

investigate the force required to pull a shoe whilst increasing the mass of it.

We were provided with the relevant apparatus and given the necessary? instructions from our teacher. The objective of the experiment was to obtain a set of

results from which we would be able to understand the relationship between

force and mass and the effect of variables on the same. Apparatus ?(see diagram 1)1. Neutron metre 2. Length of string 3. 2×500g masses 4. 5×200g masses 5. Shoe Purpose Of Preliminary Experiment 1. To see how to load the shoe ie. where to place the

masses to ensure the shoe stays in contact with the surface. 2. How to ?pull? the shoe safely. 3. How many masses to use i.e how many fit in the

shoe. 4. The range of masses i.e maximum safe mass. 5. Which forcemetre is suitable. 6. How and where to attach the forcemetre .Method1. Place the masses inside the shoe and place the shoe

on a flat surface; 2. Attach the string onto the neutron-metre and fix

the hook on the end to the end of the shoe; 3. Give a controlled tug on the neutron metre. The

measurement scale will move. Carefully observe the measurement scale. Stop

pulling when the shoe starts to move and record the pulling force displayed on

the measured scale. 4. Add the required masses to the shoe and repeat.Results Of The Preliminary Experiment 1. I will use the range of weights from 200g – 2kg.

The masses under 200g made the experiment difficult because only? a small force was needed to pull the shoe

and consequently it? was extremely

difficult to read the displayed force on the neutron metre. I found that 200g

was the first measurement that could be read accurately as it required a

considerable amount of force. Two kilograms was the maximum weight I could fit

inside the shoe, without causing damage to my shoe, and therefore the finishing

mass. 2. To ensure the shoe was pulled safely I tied a piece

of string to the neutron metre and pulled the string. 3. The forcemetre I used was a 15N neutron metre as a

13.7 neutrons was my maximum reading. 4.I attached the forcemetre to the shoe by placing the

hook of the neutron metre to the end of the shoe 5. The range of masses used were as follows :- 200g?? – 2.5N?? 400g?? – 2.9N 500g?? – 3.7N 1000g? – 6.1N 1500g? – 8.9N 2000g? – 13.7N 6. Safety Procedures (i) Make sure the weights are firmly in the shoe so it

is not possible for the weights to fall out and cause damage to the

surroundings. (ii) Place the shoe in the middle of the table to

prevent it from falling off. (iii) Do not force too many weights in the shoe as

they may damage the shoe or fall out.Variables Constant Variables ?To make this

experiment a fair test the following variables must be kept constant throughout

the experiment Ø


of shoe in contact with surface Ø


slope of surface Ø


length of string Ø


of surface under shoe Ø


of tread of sole of shoe Ø


of shoe surface in contact with surface under shoeChanging Variables – The weight of the overall shoe and the force applied

to the shoe. Dependent Variable – Pulling force. Independent Variable – Mass of shoe.Prediction?Statement: ?The greater the mass of the shoe, the greater the

force required to move the shoe.? This is because

increasing the mass will increase the friction between the shoe and the bench

(this is because the surfaces are being pushed together). If smooth looking surfaces are examined under a high power microscope,

their actual roughness can be seen. They only touch where their high spots

meet. (See fig.2) The high spots that are

touching tend to stick together. The limiting friction is the force needed to

separate these high spots. Once the high spots have been separated a lower

force is needed to keep the two surfaces moving. If the normal force is

increased the surfaces are squashed together more. The high spots, where the

surfaces are in contact, are larger:A greater limiting friction is

needed to separate the high spots and a greater dynamic friction is also needed

to keep the surfaces sliding.