## University Physics with Modern Physics (14th Edition)

The meterstick has a constant downward acceleration. We know the initial velocity of 0 m/s and the displacement. Use the kinematics formulas for constant acceleration to find the reaction time. a. Let the downward direction be positive. The meter stick has zero initial velocity and $a_y=9.80m/s^2$. Let d be the distance the meterstick falls. Use $y-y_o=v_{oy}t+0.5at^2$ $d= 0+(4.90m/s^2)t^2$ $t=\sqrt{\frac{d}{4.90m/s^2}}$ b. Evaluate for d = 0.176 m to find a reaction time of 0.190 s.