A student wants to determine the coefficients of static friction and kinetic friction between a box and a plank. She places the box on the plank and gradually raises one end of the plank. When the angle of inclination with the horizontal reaches 25°, the box starts to slip, and it slides 2.4 m down the plank in 4.1 s at constant acceleration.
(a) What is the coefficient of static friction?
(b) What is the coefficient of kinetic friction?
2007-04-25 17:28:23 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Remember Newton's Laws. Draw some free body diagrams and figure out what forces are acting on the block just before it slips and as it is sliding down the ramp.
2007-04-25 17:41:28 · answer #1 · answered by msi_cord 7 · 0⤊ 0⤋
static friction is got here upon via in basic terms appearing a sum of forces alongside the plank, it truly is mg sin (max perspective) = us mg cos (max perspective) us = tan (max perspective) kinetic friction has similarities, yet we contain the acceleration, it truly is mg sin (perspective) - uk mg cos (perspective) = m acceleration uk = (g sin(perspective) - acceleration) / (g cos (perspective)) discover the acceleration from the area and the time assuming initial speed = 0, use straightforward cinematics for this.
2016-12-04 21:28:52 · answer #2 · answered by Anonymous · 0⤊ 0⤋