A car travels in steady rain with constant acceleration. Initially rain tracks on the side window make 37° with vertical; after 20 s they make 53° with vertical in the same direction. Rain falls vertically at 3 m s⁻¹. Find car acceleration in cm s⁻².

Question

G1 Physics · Accepted Answer

Rain falls vertically at 3 m s⁻¹. Initially, tan37°=v₁/3, so v₁=3×( 3 4 \frac{3}{4} 4 3 ​ )=2.25 m s⁻¹. After 20 s, tan53°=v₂/3, so v₂=3×(4/3)=4 m s⁻¹. Therefore acceleration=(4-2.25)/20=0.0875 m s⁻²=8.75 cm s⁻². Numeric answer = 8.75. The printed source key appears inconsistent.