Question

An object, let go from rest at height h, travels 0.33h during its first second. Find the average velocity of the entire free fall.

Answer 1

For unifom acceleration, s=ut+1/2at2, where s is displacement, u is initial velocity, t is time, a is acceleration.

Here,u= 0 m/s, a=9.8 m/s2.

So, for t= 1 second, displacement s =0*1+1/2*9.8*1*1 = 4.9 m.

So,0.33 h = 4.9

=>h = 4.9/0.33 = 14.848485 m.

Now, if we consider entire motion, s=14.848485 m, u=0 m/s, a =9.8 m/s2.

So, 14.848485=0*t+1/2*9.8t2, where t is time required for entire motion.

=>t2=14.848485*2/9.8=3.0303

=>t=1.740775689 seconds.

Average velocity=displacement/time=14.848485/1.740775689=8.53 m/s.