A block $$\(B\)$$ of mass $$\(4 \mathrm{~kg}\)$$ is pushed up a line of greatest slope of a smooth plane inclined at $$\(30^{\circ}\)$$ to the horizontal by a force applied to $$\(B\)$$, acting in the direction of motion of $$\(B\)$$. The block passes through points $$\(P\)$$ and $$\(Q\)$$ with speeds $$\(12 \mathrm{~m} \mathrm{~s}^{-1}\)$$ and $$\(8 \mathrm{~m} \mathrm{~s}^{-1}\)$$ respectively. $$\(P\)$$ and $$\(Q\)$$ are $$\(10 \mathrm{~m}\)$$ apart with $$\(P\)$$ below the level of $$\(Q\)$$ Find the decrease in kinetic energy of the block as it moves from $$\(P\)$$ to $$\(Q\)$$. ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................

Answer:

Knowledge points:

Solution: