Question

a stone is dropped from a height of 20 m calculate the speed of the stone when it reach the surface g= 10 m/s square. calculate the time it takes.​

Answer 1

Explanation:

Height, s=20m

Initial velocity, u=0

Acceleration due to gravity, g=10 m/s2

Final velocity, v=?

Time taken, t=?

(i) Using relation,

s=u t+21gt2

20=0×t+21×10×t2

20=0+5t2

t2=520=4

t=4=2 s

Answer 2

Height, s=20m

Initial velocity, u=0

Acceleration due to gravity, g=10 m/s^2

Final velocity, v=?

Time taken, t=?

(i) Using relation,

s=ut+ 1/2 gt ^2

20=0×t+  1/2x10xt^2

20=0+5t^2

t^2 =  5 /20 ​=4

t=  root4  = 2s