Physics
Physics
Problem
A block is already sliding down an incline when the angle of the incline is slowly increased from to without changing the coefficient of kinetic friction. Which one of the following best describes how the magnitude of the block’s acceleration changes? a) It remains the same. b) It decreases. c) It increases. d) It becomes zero.Intuitive explanation
The key is recognizing that as the incline angle increases, two competing effects act on the block's acceleration down the slope. The component of gravity along the incline grows (speeding things up), but the normal force decreases, which reduces friction's opposing force (also speeding things up). Since both effects work in the same direction, the net acceleration must increase—friction becomes less dominant as the angle steepens.
Intuitive explanation
The key is recognizing that as the incline angle increases, two competing effects act on the block's acceleration down the slope. The component of gravity along the incline grows (speeding things up), but the normal force decreases, which reduces friction's opposing force (also speeding things up). Since both effects work in the same direction, the net acceleration must increase—friction becomes less dominant as the angle steepens.