Simple Harmonic Motion (Edexcel A Level Further Maths: Core Pure)

Exam Questions

12 mins1 question
1a
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8 marks

A company plans to build a new fairground ride. The ride will consist of a capsule that will hold the passengers and the capsule will be attached to a tall tower. The capsule is to be released from rest from a point half way up the tower and then made to oscillate in a vertical line.
The vertical displacement, x metres, of the top of the capsule below its initial position at time t seconds is modelled by the differential equation,

m fraction numerator straight d squared x over denominator straight d t squared end fraction plus 4 fraction numerator straight d x over denominator straight d t end fraction plus x equals 200 space cos space t comma      t greater or equal than 0

where m is the mass of the capsule including its passengers, in thousands of kilograms.

The maximum permissible weight for the capsule, including its passengers, is 30000N.

Taking the value of g to be 10ms-2 and assuming the capsule is at its maximum permissible weight,

(a)
(i)
explain why the value of m is 3

(ii)
show that a particular solution to the differential equation is

x space equals space 40 space sin space t space minus space 20 co s space t

(iii)
hence find the general solution of the differential equation.
1b
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4 marks
(b)
Using the model, find, to the nearest metre, the vertical distance of the top of the capsule from its initial position, 9 seconds after it is released.

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