1
\includegraphics[max width=\textwidth, alt={}, center]{f7a22c07-44e3-4891-be60-cbab772f45df-2_203_1200_264_475} A particle slides up a line of greatest slope of a smooth plane inclined at an angle \(\alpha ^ { \circ }\) to the horizontal. The particle passes through the points \(A\) and \(B\) with speeds \(2.5 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) and \(1.5 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) respectively. The distance \(A B\) is 4 m (see diagram). Find

1. the deceleration of the particle,
2. the value of \(\alpha\).