Paper Cake Case Investigation

Jade Underdown . 10S1 . JPS . 10h Nov 2002

Planning

P.2a - The Aim

I am going to drop a paper cake case from a height and record the time it takes to fall to the floor.

P8.a – The Prediction

I predict that paper cake cases that fall from a smaller distance will fall at a quicker time. However, the cake cases that fall a greater distance will have a greater speed.

P8.a – The science behind the prediction

Consulted text book of GCSE Bitesize: Falling

I predict that cases falling shorter distances will fall at a quicker time because if an object falls at 1 metre per second, the same object will fall 2 metres in 2 seconds. This will be positive correlation on a graph.

Speed is measured by Distance

Time

I predict that cases travelling further will have a greater speed. The force due to gravity of the earth becomes greater as you get closer to the core of the earth. As an object is falling, the force due to gravity increases, increasing the speed of the falling object. As the distance travelled increase, so does the increase in speed. This will be positive correlation up to a certain point on a graph, then there will be a steady speed. Eventually an object speed will become equal, no matter what distance. This is terminal velocity. It is the point at which the force due to gravity and the air resistance become balanced and so the sped stops increasing.

P8.a - The Procedure

0.2a – Safety

There are no sharp objects. Clamps should be strong enough to hold measreres, they could fall over. Paper can give paper cuts and so should be handled with care.

P6.a – Key Factors

I will be changing the height of the fall and so that is the independent variable. This will alter the time taken to fall so the time taken to fall will be the dependant variable. I will make sure the paper cake case dos not alter size or shape as this will change the time taken to fall.

P4.a ...

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P8.a - The Procedure

0.2a – Safety

There are no sharp objects. Clamps should be strong enough to hold measreres, they could fall over. Paper can give paper cuts and so should be handled with care.

P6.a – Key Factors

P4.a – Valid evidence

I will measure using the bottom of the cake case i.e. if 200cm, the bottom of the cake case is exactly 200cm from the floor level. The stopwatch will be stopped when the bottom of the cake case touches the floor. This is a precution taken to ensure that all results are as correct as possible. In order for it to be a fair test, I will replace any damaged paper cake case with one identical. By recording each fall 3 times, this reduce chances that a wrong reading is taken. If a reading looks too large or too small compared to others, will retake it.

P4.b – Suitable equipment

Measure sticks – to record how far the case has fallen.

Paper cake case – object being recorded

Stopwatch – to time how long it takes for the case to fall.

Clamp – To hold up and secure the measure stick in place.

P6.b – Extent and range of measurements

A stopwatch only measures to decimal places of a second. Between each, the reading difference would have to be significant enough to be able to differentiate. Therefore I chose that the distance range is wide. I have chosen to measure every 20 centimetres from 40cm to 200cm. All measurements are taken to 2d.p. as this is what the stopwatch shows.

P8.b - Preliminary Work

This is a few measurements taken to confirm what has been expected in the prediction.

This supports my first prediction that cases falling a smaller distance take less time. My procedure has worked well and I will continue to use it for the rest of the measurements.

Obtaining evidence

Analysing and considering evidence

I have produced a graph to compare the distance the paper cake case fell, to the average time taken for it to fall that distance.

This is positive correlation, showing that as the distance fallen increases, the time taken to fall that distance also increases. I predicted that paper cake cases that fall from a smaller distance would fall at a quicker time. My results support this theory as point 1 on the graph shows that the case fell 40 cm in 0.68 seconds. In point 2, the distance on the x-axis increases and the time on the y-axis also increases. The paper cake case that fell from a smaller distance (Point 1), fell at quicker time than Point 2, which was a greater distance.

I have produce this table using the ‘Distance fallen’ and ‘Average time taken to fall’ headed data column. I have used the Speed formula, Distance, to calculate the speed of

each cake case as fell a given distance. Time

This graph shows that the speed does not gradually increase or decrease. The speed increases up to the 160cm distance and then the speed begins to decrease towards the 200cm distance. I predicted that the cake cases that fall a greater distance will have a greater speed. I also said that at a certain point on the graph we could find the terminal velocity.

My prediction that cases that fall a greater distance will have a greater speed is supported when it is considered that point 4 is a greater distance on the x axis than point 3 and the speed of point 4 is a greater time on the y axis than point 3.

My prediction was that a certain distance, the speed would stay equal. There is no point in my results that the speed stays the same. I think this is because the paper cake case has a varied speed throughout its fall. It starts very slow due to air resistance, and then increases the more it falls due to increased pull of force due to gravity. The terminal velocity is reached after these two stages and so there is no point that we can identify exactly when the terminal velocity was reached. If a paper cake case goes through these three stages and I have taken the overall time, I do not know at what point the terminal velocity is reached and so although the results are correct, I cannot be sure this result can find if there is terminal velocity reached.