User Name Remember Me? Password

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum Mar 21st 2018, 04:20 AM #1 Junior Member   Join Date: Mar 2018 Posts: 2 1D Kinematics Motion An object falls a distance h from rest. If it travels half the height h in the last 1.00 s, find: (a) the time (b) the height h of its fall. (c) Explain the physically unacceptable solution of the quadratic equation in t that you obtain. I am trying to use the: {y=y(initial) + v(initial) - 1/2gt^2} equation to for example say that y = h/2 and y(initial) = h, assuming that the v(initial) is also 0m/s and g=9.81. Also, I am trying to apply the equation to the case where y = 0 and y(initial) = h/2, where t = 1s and v(initial) is unknown. I just can't seem to get the right answer. Thanks all.   Mar 21st 2018, 05:25 AM #2 Senior Member   Join Date: Apr 2017 Posts: 506 S = Ut +1/2f t^2 ................. S is distance traveled ........ U is initial velocity Let T be the total time of fall .... time for first part of fall is T-1 .... distance for first part of fall is h/2 ...initial velocity for first part of fall is 0 so ..... h/2= 0 + g/2 * (T-1)^2 ............................xxxxxxxxxxxxxxxxxxxx.. ................... whole fall s=h ....time of fall =T....initial velocity =0 so ..... h =0+ g/2 T^2 combining these two .... g/2 T^2 = 2*[ g/2 (T-1)^2] solving that should get the answers Valkarth likes this.  Tags gravity, kinematics Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post Aladdin Kinematics and Dynamics 8 Apr 3rd 2011 11:08 AM akshay1995 Kinematics and Dynamics 1 Dec 24th 2010 03:34 AM akshay1995 Kinematics and Dynamics 1 Dec 24th 2010 03:26 AM hah842 Kinematics and Dynamics 2 Sep 24th 2010 08:31 AM Fazil Kinematics and Dynamics 5 Mar 20th 2009 11:47 AM