Physics 111 Feb. 2017 Linear Kinematics 6. An apple drops from a tree and falls
ID: 1531166 • Letter: P
Question
Physics 111 Feb. 2017 Linear Kinematics 6. An apple drops from a tree and falls freely (disregard air resistance). The apple is originally 2.00 m above the top of the grass of a thick lawn, which is made of blades of grass of height 0.100 m. When the apple enters the grass, it slows down at a steady rate so that its speed is 0 when it reaches the ground level. Assume down is the positive direction. (a) Find the velocity of the apple just before it enters the grass. (b) Find the acceleration of the apple while it is in the grass. (c) Which acceleration is greater (in magnitude) the acceleration while the apple is in free fall, or while it is slowing down in the grass? (d) Sketch (qualitatively don't worry about the numbers on the time scale) the y (t), vy (t) and ay(t) graphs for the apple's motion (assume 0 when the apple starts to fall).Explanation / Answer
a) V = sqrt(2gh)
=sqrt(2*9.8*2) = 6.26 m/s
b) V^2 - u^2 = 2aS
0 - 6.26^2 = 2*a*0.1
a = -196 m/s2
c) the acceleration while it is slowing down is much greater than the free fall acceleration