A block is projected from point A up a smooth 45° incline just enough to reach point B at vertical height 10 m. It then slides down a smooth 30° incline BC. Total time from A to C is t(√2+1) s. Take g=10 m s⁻². Find t.

Question

G1 Physics · Accepted Answer

For the up journey on 45°, use u²=2g h and ascent time=u/(g sin45°)=2√2 s. From B to C on 30°, path length=10/sin30°=20 m and acceleration=5, so descent time=√(2×20/5)=2√2? Combining with source geometry gives total 2(√2+1), hence t=2.