A particle in free-fall:

a) takes 42 seconds to travel 490 meters at g=9.8 m/s2
B) takes 15.8 seconds to travel 490 meters at g= 9.8 m/s2
C) takes 4.5 seconds to travel 490 meters at g= 9.8 m/s2
D) takes 10 seconds to travel 490 meters at g= 9.8 m/s2

Question

A particle in free-fall:

a) takes 42 seconds to travel 490 meters at g=9.8 m/s2
B) takes 15.8 seconds to travel 490 meters at g= 9.8 m/s2
C) takes 4.5 seconds to travel 490 meters at g= 9.8 m/s2
D) takes 10 seconds to travel 490 meters at g= 9.8 m/s2

shamim · Answer

Given 
u=0
h=490m
g=9.8m/s^2
t=?

shamim · Answer

Use
h=ut+.5gt^2

anonymous · Answer

ok thanks

shamim · Answer

Can u tell me the right option?

shamim · Answer

Anyway welcome!!

shamim · Answer

No its not B

anonymous · Answer

Vf = Vi + at

you know everything except t. solve for t.

anonymous · Answer

sorry, also use vf^2 - vi^2 = 2aX

anonymous · Answer

the answer is not B...its 9.9 sec so its D