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Describe the purpose of the moderator in a nuclear fission reactor.

The moderator material is generally graphite or water. These materials do not absorb or react with the neutrons, they simply act to slow down fast moving neutrons. If neutrons are moving too quickly they ...

Answered by Samar K. • Physics tutor

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Why is light refracted when it crosses from air to glass?

To answer this question we need to know what makes glass different to air. The main difference is their refractive index. For air it's 1 and for glass it's anywhere between 1.52 - 1.54 depending on the t...

Answered by Stefania R. • Physics tutor

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Matt weighs 60kg and his son, Rob weighs 30kg. They both run a 100m race and finish the race running at 5m/s. Who has more Kinetic Energy at the end of the race?

Kinetic energy is given by the equation:K.E. = 0.5mv²Therefore Matt has Kinetic energy:K.E. (Matt) = 0.5*(60)(5)² = 750JAnd Rob has Kinetic energy:K.E. (Rob) = 0.5(30)*(5)

Answered by Lewis B. • Physics tutor

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Define the Specific Heat Capacity of a material. What is its unit?

This is the amount of energy needed to heat 1kg of the material by 1 degree: ENERGY to heat a MASS by a TEMPERATURE INCREASE.
Usingstandard units:Energyis in Joules [J]Massis in kilograms [kg]Tempera...

Answered by Laura O. • Physics tutor

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Describe the forces acting on a skydiver over time, from the moment she jumps out of the plane until hitting the ground and the effect this has on her velocity. What happens when she opens her parachute?

When the skydiver first steps out of the plane, she accelerates downwards at a high rate. At first the resultant force on her is large since gravity pulls her down, but since she is moving slowly the forc...

Answered by Siobhan P. • Physics tutor

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