3 The fixed points A and B lie on a line of greatest slope of a smooth inclined plane, with B higher than A . The horizontal distance from A to B is 2.4 m and the vertical distance is 0.7 m . The fixed point C is 2.5 m vertically above B . A light elastic string of natural length 2.2 m has one end attached to C and the other end attached to a small block of mass 9 kg which is in contact with the plane. The block is in equilibrium when it is at A, as shown in Fig. 3.
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{5a0df44f-f8f0-44d4-b2f6-70a5314706f9-4_712_641_488_687}
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\caption{Fig. 3}
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- Show that the modulus of elasticity of the string is 37.73 N .
The block starts at A and is at rest. A constant force of 18 N , acting in the direction AB , is then applied to the block so that it slides along the line AB .
- Find the magnitude and direction of the acceleration of the block
(A) when it leaves the point A ,
(B) when it reaches the point B . - Find the speed of the block when it reaches the point B .