QUESTIONS rock is dropped from the edge of a cliff 15.0 m high. How long does it
ID: 1881180 • Letter: Q
Question
QUESTIONS rock is dropped from the edge of a cliff 15.0 m high. How long does it take to reach the bottom of the cliff? 1. A 2. If the rock is projected horizontally from the same cliff with the initial speed of 2.5 m/s, how long does it take to reach the ground? If the rock is projected horizontally at the same speed (2.5 m/s) from a different cliff, and it lands at a point 7.5 m from the base of the cliff, how high is the cliff? 3. 4. A ball is dropped from a table 1.2 m high. What is the acceleration of the dropped ball just before it hits the floor?Explanation / Answer
1] Using the second equation of motion,
h = ut+ 0.5 gt^2
15 = 0 + 4.9t^2
t = sqrt(15/4.9)
= 1.75 s
2] t = 1.75 s answer
Because, equation will be same in vertical.
3] solving equation in horizontal, t = d/v = 7.5/2.5 = 3s
h = 0.5gt^2 = 4.9*3^2
= 44.1 m answer
4] acceleration a = g = 9.8 m/s^2 downward