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Two people sit opposite each other on the edge of a rotating disk of radius, R, and negligible mass. One person has a mass of 40kg, the other of 50kg. The disk is rotating at 30 revs/min. What is the rotational kinetic energy if R=1.5m?

Rotational Kinetic Energy (KE) = (1/2) x Moment of Inertia (I) x (Angular Velocity (w) ) 2 I=SUM(MR 2 ) = 40 x (1.5) 2 + 50 x (1.5) 2 = 90 x (1.5) 2 = 202.5 kgm 2 w= 30 revs / min = 30 x (2π/60) = π (rad/s)K...
JS
Answered by Joe S. • Physics tutor
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What is the meaning of the term "Specific Heat Capacity"?

Specific Heat Capacity is the amount of energy required to increase the temperature of 1kg of a substance by 1 degree Kelvin/Celsius ."Specific" refers to the fact that this value is per kilogram, ...
DM
Answered by Daragh M. • Physics tutor
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Explain why Germany thought the Treaty of Versailles was unfair

The first reason the Treaty of Versailles was perceived as unfair was the inclusion of the War Guilt Clause which was juxtaposed to German perceptions of World War I. The War Guilt clause gave culpability to...
MF
Answered by Marcus F. • History tutor
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How do conservative plate boundaries cause earthquakes?

-Tectonic plates (which can be either continental or oceanic) slide past each other either in opposite directions or in the same direction but at different speeds-This causes friction between the plates to b...
LH
Answered by Laura H. • Geography tutor
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Expand and simplify (x − 4)(2x + 3y)^2

First concentrate on expanding the squared term, don't try and do it all in your head, the 2x+3y term should expand to give 4 separate terms. Then combine any terms with the same configuration of x and y, in...
CM
Answered by Catherine M. • Maths tutor
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