On a hot summer day in the state of washington while kayaking, i saw several swimmers jump from a railroad bridge into the snohomish river below. the swimmers stepped off the bridge, and i estimated that they hit the water 1.50 s later. a.) how high was the bridge?
b.) how fast were the swimmers moving when they hit the water?
c.) what would the swimmer's drop time be if the bridge were twice as high?

Explanation:

Time taken to hit the water  t = 1.5 s

Initial vertical velocity u = 9.8 ms⁻²

Final velocity to hit the water = v

Height of the bridge = h

a ) from the formula

h = ut + 1/2 gt²

= 0 + .5 x 9.8 x 1.5²

= 11.025 m

b ) v = ?

v =  u +gt

= 0 + 9.8 x 1.5

= 14.7 ms⁻¹.

c ) If h = 2 x 11.025

= 22.05 m

h = ut + 1/2 gt²

22.05 = 0 + .5 x 9.8 t²

t² = 4.5

t = 2.12 s .

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )