Term
Describe the force of gravity. |
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Definition
| The force of gravity is an attractive force acting between any 2 objects due to their masses. |
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Term
Q1)What is a gravitational field? Q2)What is the strength of a gravitational field at a point? Q3) What do field lines tell us about a field? |
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Definition
A1) A region in which an object with mass will feel a force. A2)The strength of the field at a point is the force exerted per unit mass placed in the field. A3) The arrows on the field lines show the direction of the force of a mass placed in the field. The spacing of the lines shows the strength of the field. i.e. the farther apart the field lines, the weaker the field. |
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Term
| What is the difference between the field of a uniform spherical mass and the field of an equal point mass at the centre of the sphere? |
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Definition
| There is no difference. The fields are the same. |
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Term
| What is Newton's law of gravitation? |
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Definition
Any two point masses attract each other with a force that is proportional to each of their masses and inversly proportional to the square of the distance between them. The force between 2 point masses: F=-Gm1m2 /r2 G=6.67x10-11Nm2Kg-2 |
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Term
What is the field strength at distance r from point mass M given by? |
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Definition
g=-GM/r2 because F=gm and F=-GMm/r2 so gm=-GMm/r2 so g=-GMm/r2m
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Term
Q1)On or near the surface of the earth, how would you describe the field? Q2) What is the gravitational field strength equal to? |
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Definition
A1) On or near the surface of the earth, the field is uniform.[image]
A2) g is equal to the acceleration of free fall. |
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