# Uniformly accelerated motion- a weird kangaroo prob

by bjr_jyd15
Tags: accelerated, kangaroo, motion, prob, uniformly, weird
 P: 161 I'm an Aussie, so I should be able to help with the Kangaroo question! First off, you have more than one variable. (Assuming that the kangaroo is on the Earth) The acceleration can be given by g. (ie use -9.8 m/s/s) The displacement is 2.5m, and Vf = 0 (at the top of the jump, the kangaroo's velocity is zero). Vi is the unknown, that you want to calculate. I believe the constant acceleration formula you might need is: $$v_f^2 = v_i^2 + 2as$$ where Vf and Vi are the final and initial velocities respectively. a is the acceleration s is the displacement also don't forget the direction of things. (if you use +2.5 for the displacement, you MUST use -9.8 for the acceleration)