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

Answer 1

Use the kinematic equation:\[d=\cancel{V_it}+\frac{1}{2}at^2\]\[490m=\frac{1}{2}(9.8m/s^2)t^2\]Solve for t.

Answer 2

You'll get a positive and negative result...you can ignore the negative one since it wouldn't make sense for the time to negative.