• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Determination of the Acceleration due to Gravity on the Earth’s Surface

Extracts from this document...

Introduction

PLAN

Determination of the Acceleration due to Gravity on the Earth’s Surface

I will be investigating the acceleration due to gravity on the Earth’s surface using an experiment based on this effect. The acceleration due to gravity is constant for all objects, as it is defined by the strength of the gravitational field strength of the object, and not the mass of the object it is pulling.

Therefore, in a vacuum, all objects will accelerate at the same rate due to gravity. This only applies in a vacuum, as air resistance plays a significant role as a frictional force. The Earth’s acceleration due to gravity (also referred to as Standard Gravity, or simply g) is 9.80616ms2 (according tohttp://medical-dictionary.thefreedictionary.com/Standard+gravity), or 9.81ms-2 to three significant figures.

The weight of an object is its downwards force, which is given by the equation:

F = mg

Where F is the downwards force, or weight; m is the mass of the object; and g is the gravitational field strength of the body attracting it (this is simply g on Earth; standard gravity).

When forces are taken into account, frictional forces play a part in determining the resultant force. The downwards force of the body is constant, as the mass does not change as the body falls. However, air resistance increases with velocity, in the case of freefall under gravity.

...read more.

Middle

n/a

18.6

0.1

1.86

4.4

26.5

0.1

2.65

7.9

39.5

0.1

3.95

13

47.5

0.1

4.75

8.25

54.0

0.1

5.40

6.25

My results give an average acceleration of 7.96ms-2, which is quite satisfactory considering the effects of friction and air resistance. In the actual run, however, I will use a 200g mass, as this should further reduce the effects of these frictional forces. Therefore, the acceleration given should be closer to g.

Accuracy and Reliability

To improve the accuracy of my results, I will use a mechanical timer, which will remove human error from this process. Also, I will measure the dot-to-dot distance with a metre ruler with millimetre increments, to increase the accuracy of that process. This should give an error of ±1mm.

The time increments, height of the drop and the gravitational field strength are all constant, so the accuracy of the readings should be fairly high.

To improve reliability, I will repeat the experiment three times. The same scenario will used in each, keeping height, gravity, and time increments the same. If there are no anomalous results, then my results should be quite reliable.

Equipment

  • A.C Power supply
  • 200g mass
  • Clamp stand
  • Ticker tape timer
  • Ticker tape
  • Sellotape
  • Metre ruler
  • Connecting wires

Risk Assessment

Risk

Cautionary Procedure

Risk of electric shock if connecting wires are unsafe or bare

Check to ensure that electrical equipment is kept in safe condition

Masses dropping from height

Be aware, and raise awareness of others, that there are suspended masses

Sources Used

  • Sang, D., Gibbs, K. & Hutchings, R. (ed.) 2004, Physics 1,
  • Cambridge University Press, Cambridge, UK
  • Wikipedia 2007, Standard gravity, viewed 27 March 2007,
  • < http://en.wikipedia.org/wiki/Standard_gravity>
  • Wikipedia 2007, Pendulum, viewed 27 March 2007,
  • < http://en.wikipedia.org/wiki/Pendulum>
  • Saunders 2007, Standard gravity - definition of Standard gravity in the Medical dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclopedia., viewed 27 March 2007,
  • <http://medical-dictionary.thefreedictionary.com/Standard+gravity>

Results

First Run

Distance

(x10-2m)

Time

(s)

Speed

(ms-1)

Acceleration

(ms-2)

6.30

0.1

0.63

n/a

16.2

0.1

1.62

9.90

24.5

0.1

2.45

8.30

34.7

0.1

3.47

10.2

43.2

0.1

4.32

8.70

54.8

0.1

5.48

11.6

...read more.

Conclusion

1 – F2

        = 0.128N

Therefore, there must have been a 0.128N friction opposing the motion of the mass.

Evaluation

There were several flaws and limitations of the experiment, when it came to the actual procedure.

The tape may have run through the timer at an angle, which would have affected the vertical fall of the mass, and therefore, the distance between the dots. This would have changed the value for g that resulted.

The timer may also have been irregularly marking the tape, which would severely negate the accuracy and reliability of my results. This would have made the timing inconsistent, and the time is crucial to calculating the value of the acceleration. There was no way of knowing which dots may or may not have been anomalous, so this compounded the problem.

The tape may have had kinks or small rips in it, which would have altered its path and added to friction. This would change the position or regularity of the dots on the tape.

The reliability of the results is questionable, as the latter two graphs showed an acceleration of within 0.07ms-2 of each other, but the first graph shows a reading of 8.4ms-2,which is a whole 1ms-2 out from the others. This made a definite difference to the average value of standard gravity.

Percentage error        = (highest result – lowest result)        x 100

                                     Average result

                        = 1.07                x 100

                           9.17

                        = 11.7% error

This is a fairly large percentage error.

The error bars on my graphs, blue for maximum and black for minimum, also show how wide the possible error for my results is.

...read more.

This student written piece of work is one of many that can be found in our GCSE Forces and Motion section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Forces and Motion essays

  1. Peer reviewed

    Factors Influencing Resistance of a Wire

    3 star(s)

    This means that the length of wire and the resistance are very closely related, and directly proportional to each other.

  2. How does the weight of an object affect the friction it has on the ...

    Analysis The graphs that I have made show that the results are regular and form a strong correlation around the lines of best fit. A line of best fit was used to reduce error. In all three surfaces, the graph shows a straight line through the origin, this means that

  1. How does an increased surface area change the time taken for a mass to ...

    The accuracy of my results do seem pretty good as shown by the good fit of the line on the graph and no anomalous results appearing in graph or table.

  2. Determining the acceleration due to gravity by using simple pendulum.

    At low Earth orbit altitude, the value of g is approximately 8.9 ms-2 PREDICTION The diagram shows the arcs through which two pendulums swing. The red one is twice the length of the blue one. Notice that the short arc is always at a steeper angle than the longer arc, and always above it.

  1. Ticker Tape

    In this case it is a weight with a mass of 100 grams, which is attached to a length of ticker tape; this is held at a certain height, and then released. In this experiment gravitational potential energy, is changed to kinetic energy.

  2. In this experiment I aim to find out how the force and mass affect ...

    From the previous experiment we know that to achieve a 5� angle the ramp will be set up 10.9cm off the ground. I have gone through the method for this later. The same method will be used as before. I will use the same ball which weighs 28.07g each time even though all masses should accelerate at the same rate.

  1. Investigating the period of a simple pendulum and measuring acceleration due to gravity.

    Time for 20 oscillations(s) Time for 20 oscillations(s) 0.10 13.37 13.13 0.30 23.09 23.02 0.50 28.38 28.30 0.70 33.38 33.94 0.90 37.78 37.69 1.10 41.53 41.56 1.30 44.78 44.44 1.50 48.26 48.59 ANALYSIS: RESULTS: Length (m) Time for 20 oscillations(s) Time for 20 oscillations(s) Mean time(s) Time� (s�)

  2. The determination of the acceleration due to gravity at the surface of the earth, ...

    The period is also said to remain constant, even when the amplitude of the oscillation decrease (probably due to air resistance). This result was first obtained by Galileo, who noticed a swinging lantern and timed the oscillations by his pulse (clocks had not been invented).

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work