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Explain why the moon is not pulled away from the Earth by the Sun.

The force of gravity decreases very rapidly with distance, since force is inversely proportional to distance 2 . The Sun is much further away from the Moon than the Earth, so its gravitational attraction isn...
AP
Answered by Alicia P. • Physics tutor
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Use the chain rule to differentiate y=1/x^2-2x-1

First we will rewrite y so it is written with a power: y=1/x 2 -2x-1=(x 2 -2x-1) -1 Now let u=x 2 -2x-1 => du/dx = 2x -2 Writing y in terms of u: y=u -1 => dy/du= -u -2 = - 1/u 2 using the chain rule: ...
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Answered by Alicia P. • Maths tutor
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A house increases by 25% to £80,000. Find what it was worth before the rise.

A 15% increase means that the £80,000 represents 115% of the original value . Therefore what we do is: £80,000=£125% divided by 125 which gives us £640 = 1% then we want to multiply by 100 to change this to ...
AP
Answered by Alicia P. • Maths tutor
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Why does the basic problem of choice arise?

A detailed answer to this question would start by defining and explaining the economic term - scarcity and establishing the relationship between our infinite needs and wants and finite resources. This would ...
GM
Answered by Giorgia M. • Economics tutor
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State two components of physical fitness that an individual would need when taking part in a 100m sprint race and describe how each component could improve her performance.

There are many components of fitness which would benefit an individual's performance in a 100m sprint race, however, the two which I will focus on are explosive power, and flexibility. Explosive power will p...
CS
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