CAIE M2 (Mechanics 2) 2005 November

1
\includegraphics[max width=\textwidth, alt={}, center]{a20a6641-d771-4c89-b40f-168a0c61f99d-2_552_604_264_772} A uniform solid cone has vertical height 28 cm and base radius 6 cm . The cone is held with a point of the circumference of its base in contact with a horizontal table, and with the base making an angle of \(\theta ^ { \circ }\) with the horizontal (see diagram). When the cone is released, it moves towards the equilibrium position in which its base is in contact with the table. Show that \(\theta < 40.6\), correct to 1 decimal place.

2
\includegraphics[max width=\textwidth, alt={}, center]{a20a6641-d771-4c89-b40f-168a0c61f99d-2_456_871_1228_635} An aircraft flies horizontally at a constant speed of \(220 \mathrm {~m} \mathrm {~s} ^ { - 1 }\). Initially it is flying due east. On reaching a point \(A\) it flies in a circular arc from \(A\) to \(B\), taking 50 s . At \(B\) the aircraft is flying due south (see diagram).

1. Show that the radius of the arc is approximately 7000 m .
2. Find the magnitude of the acceleration of the aircraft while it is flying between \(A\) and \(B\).

3
\includegraphics[max width=\textwidth, alt={}, center]{a20a6641-d771-4c89-b40f-168a0c61f99d-3_293_1045_267_550} A uniform lamina \(A B C D\) is in the form of a trapezium in which \(A B\) and \(D C\) are parallel and have lengths 2 m and 3 m respectively. \(B D\) is perpendicular to the parallel sides and has length 1 m (see diagram).

1. Find the distance of the centre of mass of the lamina from \(B D\). The lamina has weight \(W \mathrm {~N}\) and is in equilibrium, suspended by a vertical string attached to the lamina at \(B\). The lamina rests on a vertical support at \(C\). The lamina is in a vertical plane with \(A B\) and \(D C\) horizontal.
2. Find, in terms of \(W\), the tension in the string and the magnitude of the force exerted on the lamina at \(C\).

4 A particle is projected from horizontal ground with speed \(u \mathrm {~m} \mathrm {~s} ^ { - 1 }\) at an angle of \(\theta ^ { \circ }\) above the horizontal. The greatest height reached by the particle is 10 m and the particle hits the ground at a distance of 40 m from the point of projection. In either order,

1. find the values of \(u\) and \(\theta\),
2. find the equation of the trajectory, in the form \(y = a x - b x ^ { 2 }\), where \(x \mathrm {~m}\) and \(y \mathrm {~m}\) are the horizontal and vertical displacements of the particle from the point of projection.

5
\includegraphics[max width=\textwidth, alt={}, center]{a20a6641-d771-4c89-b40f-168a0c61f99d-3_577_693_1740_724} A particle \(P\) of mass 0.2 kg is attached to the mid-point of a light elastic string of natural length 5.5 m and modulus of elasticity \(\lambda \mathrm { N }\). The ends of the string are attached to fixed points \(A\) and \(B\) which are at the same horizontal level and 6 m apart. \(P\) is held at rest at a point 1.25 m vertically above the mid-point of \(A B\) and then released. \(P\) travels a distance 5.25 m downwards before coming to instantaneous rest (see diagram). By considering the changes in gravitational potential energy and elastic potential energy as \(P\) travels downwards, find the value of \(\lambda\).

6
\includegraphics[max width=\textwidth, alt={}, center]{a20a6641-d771-4c89-b40f-168a0c61f99d-4_673_773_269_685} A horizontal circular disc of radius 4 m is free to rotate about a vertical axis through its centre \(O\). One end of a light inextensible rope of length 5 m is attached to a point \(A\) of the circumference of the disc, and an object \(P\) of mass 24 kg is attached to the other end of the rope. When the disc rotates with constant angular speed \(\omega\) rad s \(^ { - 1 }\), the rope makes an angle of \(\theta\) radians with the vertical and the tension in the rope is \(T \mathrm {~N}\) (see diagram). You may assume that the rope is always in the same vertical plane as the radius \(O A\) of the disc.

1. Given that \(\cos \theta = \frac { 24 } { 25 }\), find the value of \(\omega\).
2. Given instead that the speed of \(P\) is twice the speed of the point \(A\), find
   (a) the value of \(T\),
   (b) the speed of \(P\).

7 A particle of mass 0.25 kg moves in a straight line on a smooth horizontal surface. A variable resisting force acts on the particle. At time \(t \mathrm {~s}\) the displacement of the particle from a point on the line is \(x \mathrm {~m}\), and its velocity is \(( 8 - 2 x ) \mathrm { m } \mathrm { s } ^ { - 1 }\). It is given that \(x = 0\) when \(t = 0\).

1. Find the acceleration of the particle in terms of \(x\), and hence find the magnitude of the resisting force when \(x = 1\).
2. Find an expression for \(x\) in terms of \(t\).
3. Show that the particle is always less than 4 m from its initial position. \footnotetext{Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity.
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