Question

SECTION B
A body falls freely from rest, find
(a) The distance it falls in 3 seconds
(b) Its speed after falling 20m
(c) The time required to reach a speed of 25m/s.
(d) Time taken to fall 80m. (Take g = 10m/s²)

Answer 1

u = 0m/s

g = 10m/s²

a) t = 3

s = ut+½at² = 0+½×10×3² = 45m

Distance it falls in 3 seconds = 45m

b) s = 20m

v²=u²+2as

v² = 0+2×10×20

v² = 400

v = 20m/s

Speed after falling 20m = 20m/s

c)v = 25m/s

v = u+at

25 = 10t

t = 2.5s

Time taken to aquire a speed of 25m/s = 2.5s

d)s = 80m

s = ut+½at² => 80 = ½×10×t²

=>80/5 =t²

=>16 = t²

=> t = 4s

Time taken to fall to a distance of 80m = 4s

Cheers!