A student investigates friction by attaching a spring scale to a wooden block on a…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A student investigates friction by attaching a spring scale to a 1.0kg wooden block on a horizontal rough board. Pulling horizontally, the student records the steady reading of the scale at various moments. The block remains at rest until the recorded force reaches 14N, after which the reading drops and fluctuates around 10N while the block slides at constant speed.
(a) Using the description above, draw a qualitative graph of the friction-force magnitude on the block as a function of the applied force from 0N to 18N. Clearly indicate the breakaway point and the kinetic-friction plateau.
(b) From the graph or information provided, determine the coefficient of static friction between the block and the board.
(c) Determine the coefficient of kinetic friction between the block and the board.
(d) Identify two reasonable sources of experimental uncertainty in this method and explain how each could affect the calculated coefficients.