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
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
Area
of shoe in contact with surface Ø
The
slope of surface Ø
The
length of string Ø
Type
of surface under shoe Ø
Thickness
of tread of sole of shoe Ø
Nature
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.