• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2
3. 3
3
4. 4
4
5. 5
5
6. 6
6
7. 7
7
8. 8
8

# Determination of the Acceleration due to Gravity on the Earth&amp;#8217;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.

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

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.

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

# Related GCSE Forces and Motion essays

1. ## Determining the acceleration due to gravity by using simple pendulum.

For these reasons as the string gets longer the time per swing will get longer RESULTS Length of Pendulum (l) (m) 20 Swings Average (s) 1 Swing (T) (s)

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

There are no anomalous results for me to comment on since all the points are close to the straight line. This maybe because the equipment I used to measure the length and the time period are quiet accurate. This is proved by the fact that when I worked out the

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

Apparatus: - A rectangular block of wood (325g) - A spring balance, also called a force meter - A piece of string - Surfaces: Plastic surface of the table, wooden surface, sand paper (3M210-p120), sand paper (P60E green). - 10g, 25g, 100g and 200g weights - An electronic scale Method: A block of wood will be attached to

2. ## Ticker Tape

When the weight hit the ground the power supply to the ticker timer was immediately disconnected. This was done so that no extra dots were added to the trace when the weight was resting, ensuring the most accurate reading that was possible.

1. ## Investigate the effects of an asteroid impact on Earth through a small-scale simulation.

The mass of the asteroid, as the greater this is the larger the impact area; the asteroid's velocity, as the faster an object collides with something, the more energy is transferred. Both the mass and velocity determine the momentum and thus kinetic energy that the asteroid has - this is

2. ## Investigation into Friction.

For Graph 1, the smooth hardboard, the distances of the plotted points from the line of best fit are as follows in Table 5. Weight (R) / N Average reading on force meter (F)

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

Terminal velocity is achieved by Newton's 1st law: Balanced forces do not affect the movement of an object: it remains stationary. But in this case Newton also says if the object is already moving it continues to move at the same speed and in the same direction.

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