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Two cars are crash tested. Car A has a crumple zone, B doesn't. Both cars have mass 1500kg and a driver of mass 80kg and crash at 20m/s. Cars A and B take 0.8 and 0.2 seconds to stop respectively. Using this information, are crumple zones a necessity? (6)

We need to show that car A is safer than car B and this is done by showing that the force is greater on car B than car A. Start by finding the force on car A, total mass 1580kg: Force is the change of moment...
JF
Answered by Jake F. • Physics tutor
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Mark has a voucher that gives him 22% off the prices at a hardware store. Estimate how much he will pay for an electric drill that normally costs £87.99. (non-calculator) (3)

It is important to remember this is an estimate, so we can simplify the numbers by saying they get 20% off and the drill costs £90. (1) 10% off would be £9, so 20% off is £18. (1) They have 20% off so they p...
JF
Answered by Jake F. • Maths tutor
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Simplify (7+sqrt(5))/(sqrt(5)-1), leaving the answer in the form a+b*sqrt(5)

Step 1 - Identify the difference bet ween the required form of the answer and the expression to be simplified: It can be seen that in order to simplify the expression we need to somehow get rid of the denomi...
IR
Answered by Ian R. • Maths tutor
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What is non-disjunction? How can this lead to changes in chromosome number?

Non-disjunction is the failure of chromosome pairs to separate properly during meiosis. This failure of separation usually occurs either in meiosis I (in anaphase I) or in meiosis II (in anaphase II). The co...
KW
Answered by Katy W. • Biology tutor
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How does evolution occur by natural selection?

Over time many theories have been put forward by the scientific community about how the process of evolution occurs. However the most commonly accepted theory amongst scientists is that evolution occurs by t...
KW
Answered by Katy W. • Biology tutor
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